Chapter 5 MySQL Server Administration

Table of Contents

5.1 The MySQL Server
5.1.1 Configuring the Server
5.1.2 Server Configuration Defaults
5.1.3 Server Option, System Variable, and Status Variable Reference
5.1.4 Server System Variable Reference
5.1.5 Server Status Variable Reference
5.1.6 Server Command Options
5.1.7 Server System Variables
5.1.8 Using System Variables
5.1.9 Server Status Variables
5.1.10 Server SQL Modes
5.1.11 IPv6 Support
5.1.12 MySQL Server Time Zone Support
5.1.13 Server-Side Help
5.1.14 Server Response to Signals
5.1.15 The Server Shutdown Process
5.2 The MySQL Data Directory
5.3 The mysql System Database
5.4 MySQL Server Logs
5.4.1 Selecting General Query Log and Slow Query Log Output Destinations
5.4.2 The Error Log
5.4.3 The General Query Log
5.4.4 The Binary Log
5.4.5 The Slow Query Log
5.4.6 The DDL Log
5.4.7 Server Log Maintenance
5.5 MySQL Server Plugins
5.5.1 Installing and Uninstalling Plugins
5.5.2 Obtaining Server Plugin Information
5.5.3 MySQL Enterprise Thread Pool
5.6 MySQL Server User-Defined Functions
5.6.1 Installing and Uninstalling User-Defined Functions
5.6.2 Obtaining User-Defined Function Information
5.7 Running Multiple MySQL Instances on One Machine
5.7.1 Setting Up Multiple Data Directories
5.7.2 Running Multiple MySQL Instances on Windows
5.7.3 Running Multiple MySQL Instances on Unix
5.7.4 Using Client Programs in a Multiple-Server Environment
5.8 Tracing mysqld Using DTrace
5.8.1 mysqld DTrace Probe Reference

MySQL Server (mysqld) is the main program that does most of the work in a MySQL installation. This chapter provides an overview of MySQL Server and covers general server administration:

For additional information on administrative topics, see also:

5.1 The MySQL Server

mysqld is the MySQL server. The following discussion covers these MySQL server configuration topics:

  • Startup options that the server supports. You can specify these options on the command line, through configuration files, or both.

  • Server system variables. These variables reflect the current state and values of the startup options, some of which can be modified while the server is running.

  • Server status variables. These variables contain counters and statistics about runtime operation.

  • How to set the server SQL mode. This setting modifies certain aspects of SQL syntax and semantics, for example for compatibility with code from other database systems, or to control the error handling for particular situations.

  • Configuring and using IPv6 support.

  • Configuring and using time zone support.

  • Server-side help capabilities.

  • The server shutdown process. There are performance and reliability considerations depending on the type of table (transactional or nontransactional) and whether you use replication.

Note

Not all storage engines are supported by all MySQL server binaries and configurations. To find out how to determine which storage engines your MySQL server installation supports, see Section 13.7.5.17, “SHOW ENGINES Syntax”.

5.1.1 Configuring the Server

The MySQL server, mysqld, has many command options and system variables that can be set at startup to configure its operation. To determine the default command option and system variable values used by the server, execute this command:

shell> mysqld --verbose --help

The command produces a list of all mysqld options and configurable system variables. Its output includes the default option and variable values and looks something like this:

abort-slave-event-count           0
allow-suspicious-udfs             FALSE
archive                           ON
auto-increment-increment          1
auto-increment-offset             1
autocommit                        TRUE
automatic-sp-privileges           TRUE
back-log                          80
basedir                           /home/jon/bin/mysql-5.6/
...
tmpdir                            /tmp
transaction-alloc-block-size      8192
transaction-isolation             REPEATABLE-READ
transaction-prealloc-size         4096
transaction-read-only             FALSE
updatable-views-with-limit        YES
verbose                           TRUE
wait-timeout                      28800

To see the current system variable values actually used by the server as it runs, connect to it and execute this statement:

mysql> SHOW VARIABLES;

To see some statistical and status indicators for a running server, execute this statement:

mysql> SHOW STATUS;

System variable and status information also is available using the mysqladmin command:

shell> mysqladmin variables
shell> mysqladmin extended-status

For a full description of all command options, system variables, and status variables, see these sections:

More detailed monitoring information is available from the Performance Schema; see Chapter 22, MySQL Performance Schema.

MySQL uses algorithms that are very scalable, so you can usually run with very little memory. However, normally better performance results from giving MySQL more memory.

When tuning a MySQL server, the two most important variables to configure are key_buffer_size and table_open_cache. You should first feel confident that you have these set appropriately before trying to change any other variables.

The following examples indicate some typical variable values for different runtime configurations.

  • If you have at least 1-2GB of memory and many tables and want maximum performance with a moderate number of clients, use something like this:

    shell> mysqld_safe --key_buffer_size=384M --table_open_cache=4000 \
               --sort_buffer_size=4M --read_buffer_size=1M &
    
  • If you have only 256MB of memory and only a few tables, but you still do a lot of sorting, you can use something like this:

    shell> mysqld_safe --key_buffer_size=64M --sort_buffer_size=1M
    

    If there are very many simultaneous connections, swapping problems may occur unless mysqld has been configured to use very little memory for each connection. mysqld performs better if you have enough memory for all connections.

  • With little memory and lots of connections, use something like this:

    shell> mysqld_safe --key_buffer_size=512K --sort_buffer_size=100K \
               --read_buffer_size=100K &
    

    Or even this:

    shell> mysqld_safe --key_buffer_size=512K --sort_buffer_size=16K \
               --table_open_cache=32 --read_buffer_size=8K \
               --net_buffer_length=1K &
    

If you are performing GROUP BY or ORDER BY operations on tables that are much larger than your available memory, increase the value of read_rnd_buffer_size to speed up the reading of rows following sorting operations.

You can make use of the example option files included with your MySQL distribution; see Section 5.1.2, “Server Configuration Defaults”.

If you specify an option on the command line for mysqld or mysqld_safe, it remains in effect only for that invocation of the server. To use the option every time the server runs, put it in an option file. See Section 4.2.6, “Using Option Files”.

5.1.2 Server Configuration Defaults

The MySQL server has many operating parameters, which you can change at server startup using command-line options or configuration files (option files). It is also possible to change many parameters at runtime. For general instructions on setting parameters at startup or runtime, see Section 5.1.6, “Server Command Options”, and Section 5.1.7, “Server System Variables”.

5.1.2.1 Changes to Server Defaults

Beginning with MySQL 5.6.6, several MySQL Server parameter defaults differ from the defaults in previous releases. The motivation for these changes is to provide better out-of-box performance and to reduce the need for database administrators to change settings manually.

In some cases, a parameter has a different fixed default value. In other cases, the server autosizes a parameter at startup using a formula based on other related parameters or server host configuration, rather than using a fixed value. For example, the setting for back_log is its previous default of 50, adjusted up by an amount proportional to the value of max_connections. The idea behind autosizing is that when the server has information available to make a decision about a parameter setting likely to be better than a fixed default, it will.

The following table summarizes changes to defaults. The Version column indicates when each default changed. For variables that are autosized, the main variable description provides additional detail about the sizing algorithm. See Section 5.1.7, “Server System Variables”, and Section 14.14, “InnoDB Startup Options and System Variables”. Any of these default settings can be overridden by specifying an explicit value at server startup.

Table 5.1 Changes to Server Defaults in MySQL 5.6

Parameter Old Default New Default Version
back_log 50 Autosized using max_connections 5.6.6
binlog_checksum NONE CRC32 5.6.6
--binlog-row-event-max-size 1024 8192 5.6.6
flush_time 1800 (on Windows) 0 5.6.6
host_cache_size 128 Autosized using max_connections 5.6.8
innodb_autoextend_increment 8 64 5.6.6
innodb_buffer_pool_instances 1 8 (platform dependent) 5.6.6
innodb_concurrency_tickets 500 5000 5.6.6
innodb_data_file_path ibdata1:10M:autoextend ibdata1:12M:autoextend 5.6.7
innodb_file_per_table 0 1 5.6.6
innodb_log_file_size 5MB 48MB 5.6.8
innodb_old_blocks_time 0 1000 5.6.6
innodb_open_files 300 Autosized using innodb_file_per_table, table_open_cache 5.6.6
innodb_stats_on_metadata ON OFF 5.6.6
join_buffer_size 128KB 256KB 5.6.6
max_allowed_packet 1MB 4MB 5.6.6
max_connect_errors 10 100 5.6.6
open_files_limit 0 Autosized using max_connections 5.6.8
performance_schema OFF ON 5.6.6
performance_schema_events_waits_history_long_size 10000 Autosized 5.6.6
performance_schema_events_waits_history_size 10 Autosized 5.6.6
performance_schema_max_cond_instances 1000 Autosized 5.6.6
performance_schema_max_file_instances 10000 Autosized 5.6.6
performance_schema_max_mutex_instances 1000000 Autosized 5.6.6
performance_schema_max_rwlock_instances 1000000 Autosized 5.6.6
performance_schema_max_table_handles 100000 Autosized 5.6.6
performance_schema_max_table_instances 50000 Autosized 5.6.6
performance_schema_max_thread_instances 1000 Autosized 5.6.6
query_cache_size 0 1M 5.6.8
query_cache_type ON OFF 5.6.8
secure_auth OFF ON 5.6.7
sql_mode '' (empty string) NO_ENGINE_SUBSTITUTION 5.6.6
sync_master_info 0 10000 5.6.6
sync_relay_log 0 10000 5.6.6
sync_relay_log_info 0 10000 5.6.6
table_definition_cache 400 Autosized using table_open_cache 5.6.8
table_open_cache 400 2000 5.6.8
thread_cache_size 0 Autosized using max_connections 5.6.8

In MySQL 5.6.6, the default for innodb_checksum_algorithm was changed from INNODB to CRC32. For compatibility reasons, the default was returned in 5.6.7 to INNODB.

5.1.2.2 Using a Sample Default Server Configuration File

On Unix platforms, mysql_install_db creates a default option file named my.cnf in the base installation directory. This file is created from a template included in the distribution package named my-default.cnf. You can find the template in or under the base installation directory. When started using mysqld_safe, the server uses my.cnf file by default. If my.cnf already exists, mysql_install_db assumes it to be in use and writes a new file named my-new.cnf instead.

With one exception, the settings in the default option file are commented and have no effect. The exception is that the file changes the sql_mode system variable from its default of NO_ENGINE_SUBSTITUTION to also include STRICT_TRANS_TABLES:

sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES

This setting produces a server configuration that results in errors rather than warnings for bad data in operations that modify transactional tables. See Section 5.1.10, “Server SQL Modes”.

The my-default.cnf template replaces the older sample option files formerly supplied with MySQL distributions (my-small.cnf, my-medium.cnf, my-large.cnf, and my-huge.cnf).

On Windows, MySQL Installer interacts with the user and creates a file named my.ini in the base installation directory as the default option file. If you install on Windows from a Zip archive, you can copy the my-default.ini template file in the base installation directory to my.ini and use the latter as the default option file.

Note

On Windows, the .ini or .cnf option file extension might not be displayed.

On any platform, after completing the installation process, you can edit the default option file at any time to modify the parameters used by the server. For example, to use a parameter setting in the file that is commented with a # character at the beginning of the line, remove the #, and modify the parameter value if necessary. To disable a To disable a setting, either add a # to the beginning of the line or remove it.

For additional information about option file format and syntax, see Section 4.2.6, “Using Option Files”.

5.1.3 Server Option, System Variable, and Status Variable Reference

The following table lists all command-line options, system variables, and status variables applicable within mysqld.

The table lists command-line options (Cmd-line), options valid in configuration files (Option file), server system variables (System Var), and status variables (Status var) in one unified list, with an indication of where each option or variable is valid. If a server option set on the command line or in an option file differs from the name of the corresponding system variable, the variable name is noted immediately below the corresponding option. For system and status variables, the scope of the variable (Var Scope) is Global, Session, or both. Please see the corresponding item descriptions for details on setting and using the options and variables. Where appropriate, direct links to further information about the items are provided.

For a version of this table that is specific to NDB Cluster, see Section 18.3.2.5, “NDB Cluster mysqld Option and Variable Reference”.

Table 5.2 Command-Line Option, System Variable, and Status Variable Summary

Name Cmd-Line Option File System Var Status Var Var Scope Dynamic
abort-slave-event-count Yes Yes
Aborted_clients Yes Global No
Aborted_connects Yes Global No
allow-suspicious-udfs Yes Yes
ansi Yes Yes
audit-log Yes Yes
audit_log_buffer_size Yes Yes Yes Global No
audit_log_connection_policy Yes Yes Yes Global Yes
audit_log_current_session Yes Both No
Audit_log_current_size Yes Global No
Audit_log_event_max_drop_size Yes Global No
Audit_log_events Yes Global No
Audit_log_events_filtered Yes Global No
Audit_log_events_lost Yes Global No
Audit_log_events_written Yes Global No
audit_log_exclude_accounts Yes Yes Yes Global Yes
audit_log_file Yes Yes Yes Global No
audit_log_flush Yes Global Yes
audit_log_format Yes Yes Yes Global No
audit_log_include_accounts Yes Yes Yes Global Yes
audit_log_policy Yes Yes Yes Global Varies
audit_log_rotate_on_size Yes Yes Yes Global Yes
audit_log_statement_policy Yes Yes Yes Global Yes
audit_log_strategy Yes Yes Yes Global No
Audit_log_total_size Yes Global No
Audit_log_write_waits Yes Global No
authentication_windows_log_level Yes Yes Yes Global No
authentication_windows_use_principal_name Yes Yes Yes Global No
auto_increment_increment Yes Both Yes
auto_increment_offset Yes Both Yes
autocommit Yes Yes Yes Both Yes
automatic_sp_privileges Yes Global Yes
avoid_temporal_upgrade Yes Yes Yes Global Yes
back_log Yes Global No
basedir Yes Yes Yes Global No
big-tables Yes Yes Both Yes
- Variable: big_tables Yes Both Yes
bind-address Yes Yes Global No
- Variable: bind_address Yes Global No
Binlog_cache_disk_use Yes Global No
binlog_cache_size Yes Yes Yes Global Yes
Binlog_cache_use Yes Global No
binlog-checksum Yes Yes
binlog_checksum Yes Global Yes
binlog_direct_non_transactional_updates Yes Yes Yes Both Yes
binlog-do-db Yes Yes
binlog_error_action Yes Yes Yes Global Yes
binlog-format Yes Yes Both Yes
- Variable: binlog_format Yes Both Yes
binlog_gtid_simple_recovery Yes Yes Yes Global No
binlog-ignore-db Yes Yes
binlog_max_flush_queue_time Yes Global Yes
binlog_order_commits Yes Global Yes
binlog-row-event-max-size Yes Yes
binlog_row_image Yes Yes Yes Both Yes
binlog-rows-query-log-events Yes Yes
- Variable: binlog_rows_query_log_events
binlog_rows_query_log_events Yes Yes Yes Both Yes
Binlog_stmt_cache_disk_use Yes Global No
binlog_stmt_cache_size Yes Yes Yes Global Yes
Binlog_stmt_cache_use Yes Global No
binlogging_impossible_mode Yes Yes Yes Both Yes
block_encryption_mode Yes Yes Yes Both Yes
bootstrap Yes Yes
bulk_insert_buffer_size Yes Yes Yes Both Yes
Bytes_received Yes Both No
Bytes_sent Yes Both No
character_set_client Yes Both Yes
character-set-client-handshake Yes Yes
character_set_connection Yes Both Yes
character_set_database (note 1) Yes Both Yes
character-set-filesystem Yes Yes Both Yes
- Variable: character_set_filesystem Yes Both Yes
character_set_results Yes Both Yes
character-set-server Yes Yes Both Yes
- Variable: character_set_server Yes Both Yes
character_set_system Yes Global No
character-sets-dir Yes Yes Global No
- Variable: character_sets_dir Yes Global No
chroot Yes Yes
collation_connection Yes Both Yes
collation_database (note 1) Yes Both Yes
collation-server Yes Yes Both Yes
- Variable: collation_server Yes Both Yes
Com_admin_commands Yes Both No
Com_alter_db Yes Both No
Com_alter_db_upgrade Yes Both No
Com_alter_event Yes Both No
Com_alter_function Yes Both No
Com_alter_procedure Yes Both No
Com_alter_server Yes Both No
Com_alter_table Yes Both No
Com_alter_tablespace Yes Both No
Com_alter_user Yes Both No
Com_analyze Yes Both No
Com_assign_to_keycache Yes Both No
Com_begin Yes Both No
Com_binlog Yes Both No
Com_call_procedure Yes Both No
Com_change_db Yes Both No
Com_change_master Yes Both No
Com_check Yes Both No
Com_checksum Yes Both No
Com_commit Yes Both No
Com_create_db Yes Both No
Com_create_event Yes Both No
Com_create_function Yes Both No
Com_create_index Yes Both No
Com_create_procedure Yes Both No
Com_create_server Yes Both No
Com_create_table Yes Both No
Com_create_trigger Yes Both No
Com_create_udf Yes Both No
Com_create_user Yes Both No
Com_create_view Yes Both No
Com_dealloc_sql Yes Both No
Com_delete Yes Both No
Com_delete_multi Yes Both No
Com_do Yes Both No
Com_drop_db Yes Both No
Com_drop_event Yes Both No
Com_drop_function Yes Both No
Com_drop_index Yes Both No
Com_drop_procedure Yes Both No
Com_drop_server Yes Both No
Com_drop_table Yes Both No
Com_drop_trigger Yes Both No
Com_drop_user Yes Both No
Com_drop_view Yes Both No
Com_empty_query Yes Both No
Com_execute_sql Yes Both No
Com_flush Yes Both No
Com_get_diagnostics Yes Both No
Com_grant Yes Both No
Com_ha_close Yes Both No
Com_ha_open Yes Both No
Com_ha_read Yes Both No
Com_help Yes Both No
Com_insert Yes Both No
Com_insert_select Yes Both No
Com_install_plugin Yes Both No
Com_kill Yes Both No
Com_load Yes Both No
Com_lock_tables Yes Both No
Com_optimize Yes Both No
Com_preload_keys Yes Both No
Com_prepare_sql Yes Both No
Com_purge Yes Both No
Com_purge_before_date Yes Both No
Com_release_savepoint Yes Both No
Com_rename_table Yes Both No
Com_rename_user Yes Both No
Com_repair Yes Both No
Com_replace Yes Both No
Com_replace_select Yes Both No
Com_reset Yes Both No
Com_resignal Yes Both No
Com_revoke Yes Both No
Com_revoke_all Yes Both No
Com_rollback Yes Both No
Com_rollback_to_savepoint Yes Both No
Com_savepoint Yes Both No
Com_select Yes Both No
Com_set_option Yes Both No
Com_show_authors Yes Both No
Com_show_binlog_events Yes Both No
Com_show_binlogs Yes Both No
Com_show_charsets Yes Both No
Com_show_collations Yes Both No
Com_show_contributors Yes Both No
Com_show_create_db Yes Both No
Com_show_create_event Yes Both No
Com_show_create_func Yes Both No
Com_show_create_proc Yes Both No
Com_show_create_table Yes Both No
Com_show_create_trigger Yes Both No
Com_show_databases Yes Both No
Com_show_engine_logs Yes Both No
Com_show_engine_mutex Yes Both No
Com_show_engine_status Yes Both No
Com_show_errors Yes Both No
Com_show_events Yes Both No
Com_show_fields Yes Both No
Com_show_function_code Yes Both No
Com_show_function_status Yes Both No
Com_show_grants Yes Both No
Com_show_keys Yes Both No
Com_show_master_status Yes Both No
Com_show_ndb_status Yes Both No
Com_show_new_master Yes Both No
Com_show_open_tables Yes Both No
Com_show_plugins Yes Both No
Com_show_privileges Yes Both No
Com_show_procedure_code Yes Both No
Com_show_procedure_status Yes Both No
Com_show_processlist Yes Both No
Com_show_profile Yes Both No
Com_show_profiles Yes Both No
Com_show_relaylog_events Yes Both No
Com_show_slave_hosts Yes Both No
Com_show_slave_status Yes Both No
Com_show_status Yes Both No
Com_show_storage_engines Yes Both No
Com_show_table_status Yes Both No
Com_show_tables Yes Both No
Com_show_triggers Yes Both No
Com_show_variables Yes Both No
Com_show_warnings Yes Both No
Com_signal Yes Both No
Com_slave_start Yes Both No
Com_slave_stop Yes Both No
Com_stmt_close Yes Both No
Com_stmt_execute Yes Both No
Com_stmt_fetch Yes Both No
Com_stmt_prepare Yes Both No
Com_stmt_reprepare Yes Both No
Com_stmt_reset Yes Both No
Com_stmt_send_long_data Yes Both No
Com_truncate Yes Both No
Com_uninstall_plugin Yes Both No
Com_unlock_tables Yes Both No
Com_update Yes Both No
Com_update_multi Yes Both No
Com_xa_commit Yes Both No
Com_xa_end Yes Both No
Com_xa_prepare Yes Both No
Com_xa_recover Yes Both No
Com_xa_rollback Yes Both No
Com_xa_start Yes Both No
completion_type Yes Yes Yes Both Yes
Compression Yes Session No
concurrent_insert Yes Yes Yes Global Yes
connect_timeout Yes Yes Yes Global Yes
Connection_control_delay_generated Yes Global No
connection_control_failed_connections_threshold Yes Yes Yes Global Yes
connection_control_max_connection_delay Yes Yes Yes Global Yes
connection_control_min_connection_delay Yes Yes Yes Global Yes
Connection_errors_accept Yes Global No
Connection_errors_internal Yes Global No
Connection_errors_max_connections Yes Global No
Connection_errors_peer_address Yes Global No
Connection_errors_select Yes Global No
Connection_errors_tcpwrap Yes Global No
Connections Yes Global No
console Yes Yes
core-file Yes Yes
core_file Yes Global No
create_old_temporals Yes Yes Yes Global No
Created_tmp_disk_tables Yes Both No
Created_tmp_files Yes Global No
Created_tmp_tables Yes Both No
daemon_memcached_enable_binlog Yes Yes Yes Global No
daemon_memcached_engine_lib_name Yes Yes Yes Global No
daemon_memcached_engine_lib_path Yes Yes Yes Global No
daemon_memcached_option Yes Yes Yes Global No
daemon_memcached_r_batch_size Yes Yes Yes Global No
daemon_memcached_w_batch_size Yes Yes Yes Global No
datadir Yes Yes Yes Global No
date_format Yes Global No
datetime_format Yes Global No
debug Yes Yes Yes Both Yes
debug_sync Yes Session Yes
debug-sync-timeout Yes Yes
default-authentication-plugin Yes Yes
default-storage-engine Yes Yes Both Yes
- Variable: default_storage_engine Yes Both Yes
default-time-zone Yes Yes
default_tmp_storage_engine Yes Yes Yes Both Yes
default_week_format Yes Yes Yes Both Yes
defaults-extra-file Yes
defaults-file Yes
defaults-group-suffix Yes
delay-key-write Yes Yes Global Yes
- Variable: delay_key_write Yes Global Yes
Delayed_errors Yes Global No
delayed_insert_limit Yes Yes Yes Global Yes
Delayed_insert_threads Yes Global No
delayed_insert_timeout Yes Yes Yes Global Yes
delayed_queue_size Yes Yes Yes Global Yes
Delayed_writes Yes Global No
des-key-file Yes Yes
disable-gtid-unsafe-statements Yes Yes Yes Global No
disable_gtid_unsafe_statements Yes Yes Yes Global No
disconnect_on_expired_password Yes Yes Yes Global No
disconnect-slave-event-count Yes Yes
div_precision_increment Yes Yes Yes Both Yes
enable-named-pipe Yes Yes
- Variable: named_pipe
end_markers_in_json Yes Both Yes
enforce-gtid-consistency Yes Yes Yes Global No
enforce_gtid_consistency Yes Yes Yes Global No
engine-condition-pushdown Yes Yes Both Yes
- Variable: engine_condition_pushdown Yes Both Yes
eq_range_index_dive_limit Yes Both Yes
error_count Yes Session No
event-scheduler Yes Yes Global Yes
- Variable: event_scheduler Yes Global Yes
exit-info Yes Yes
expire_logs_days Yes Yes Yes Global Yes
explicit_defaults_for_timestamp Yes Yes Yes Both Yes
external-locking Yes Yes
- Variable: skip_external_locking
external_user Yes Session No
federated Yes Yes
Firewall_access_denied Yes Global No
Firewall_access_granted Yes Global No
Firewall_cached_entries Yes Global No
flush Yes Yes Yes Global Yes
Flush_commands Yes Global No
flush_time Yes Yes Yes Global Yes
foreign_key_checks Yes Both Yes
ft_boolean_syntax Yes Yes Yes Global Yes
ft_max_word_len Yes Yes Yes Global No
ft_min_word_len Yes Yes Yes Global No
ft_query_expansion_limit Yes Yes Yes Global No
ft_stopword_file Yes Yes Yes Global No
gdb Yes Yes
general-log Yes Yes Global Yes
- Variable: general_log Yes Global Yes
general_log_file Yes Yes Yes Global Yes
group_concat_max_len Yes Yes Yes Both Yes
gtid_done Yes Both No
gtid_executed Yes Both No
gtid_lost Yes Global No
gtid-mode Yes Yes Global No
- Variable: gtid_mode Yes Global No
gtid_mode Yes Global No
gtid_next Yes Session Yes
gtid_owned Yes Both No
gtid_purged Yes Global Yes
Handler_commit Yes Both No
Handler_delete Yes Both No
Handler_discover Yes Both No
Handler_external_lock Yes Both No
Handler_mrr_init Yes Both No
Handler_prepare Yes Both No
Handler_read_first Yes Both No
Handler_read_key Yes Both No
Handler_read_last Yes Both No
Handler_read_next Yes Both No
Handler_read_prev Yes Both No
Handler_read_rnd Yes Both No
Handler_read_rnd_next Yes Both No
Handler_rollback Yes Both No
Handler_savepoint Yes Both No
Handler_savepoint_rollback Yes Both No
Handler_update Yes Both No
Handler_write Yes Both No
have_compress Yes Global No
have_crypt Yes Global No
have_csv Yes Global No
have_dynamic_loading Yes Global No
have_geometry Yes Global No
have_innodb Yes Global No
have_ndbcluster Yes Global No
have_openssl Yes Global No
have_partitioning Yes Global No
have_profiling Yes Global No
have_query_cache Yes Global No
have_rtree_keys Yes Global No
have_ssl Yes Global No
have_symlink Yes Global No
help Yes Yes
host_cache_size Yes Global Yes
hostname Yes Global No
identity Yes Session Yes
ignore-builtin-innodb Yes Yes Global No
- Variable: ignore_builtin_innodb Yes Global No
ignore-db-dir Yes Yes
ignore_db_dirs Yes Global No
init_connect Yes Yes Yes Global Yes
init-file Yes Yes Global No
- Variable: init_file Yes Global No
init_slave Yes Yes Yes Global Yes
innodb Yes Yes
innodb_adaptive_flushing Yes Yes Yes Global Yes
innodb_adaptive_flushing_lwm Yes Yes Yes Global Yes
innodb_adaptive_hash_index Yes Yes Yes Global Yes
innodb_adaptive_max_sleep_delay Yes Yes Yes Global Yes
innodb_additional_mem_pool_size Yes Yes Yes Global No
innodb_api_bk_commit_interval Yes Yes Yes Global Yes
innodb_api_disable_rowlock Yes Yes Yes Global No
innodb_api_enable_binlog Yes Yes Yes Global No
innodb_api_enable_mdl Yes Yes Yes Global No
innodb_api_trx_level Yes Yes Yes Global Yes
innodb_autoextend_increment Yes Yes Yes Global Yes
innodb_autoinc_lock_mode Yes Yes Yes Global No
Innodb_available_undo_logs Yes Global No
Innodb_buffer_pool_bytes_data Yes Global No
Innodb_buffer_pool_bytes_dirty Yes Global No
innodb_buffer_pool_dump_at_shutdown Yes Yes Yes Global Yes
innodb_buffer_pool_dump_now Yes Yes Yes Global Yes
Innodb_buffer_pool_dump_status Yes Global No
innodb_buffer_pool_filename Yes Yes Yes Global Yes
innodb_buffer_pool_instances Yes Yes Yes Global No
innodb_buffer_pool_load_abort Yes Yes Yes Global Yes
innodb_buffer_pool_load_at_startup Yes Yes Yes Global No
innodb_buffer_pool_load_now Yes Yes Yes Global Yes
Innodb_buffer_pool_load_status Yes Global No
Innodb_buffer_pool_pages_data Yes Global No
Innodb_buffer_pool_pages_dirty Yes Global No
Innodb_buffer_pool_pages_flushed Yes Global No
Innodb_buffer_pool_pages_free Yes Global No
Innodb_buffer_pool_pages_latched Yes Global No
Innodb_buffer_pool_pages_misc Yes Global No
Innodb_buffer_pool_pages_total Yes Global No
Innodb_buffer_pool_read_ahead Yes Global No
Innodb_buffer_pool_read_ahead_evicted Yes Global No
Innodb_buffer_pool_read_ahead_rnd Yes Global No
Innodb_buffer_pool_read_requests Yes Global No
Innodb_buffer_pool_reads Yes Global No
innodb_buffer_pool_size Yes Yes Yes Global No
Innodb_buffer_pool_wait_free Yes Global No
Innodb_buffer_pool_write_requests Yes Global No
innodb_change_buffer_max_size Yes Yes Yes Global Yes
innodb_change_buffering Yes Yes Yes Global Yes
innodb_change_buffering_debug Yes Yes Yes Global Yes
innodb_checksum_algorithm Yes Yes Yes Global Yes
innodb_checksums Yes Yes Yes Global No
innodb_cmp_per_index_enabled Yes Yes Yes Global Yes
innodb_commit_concurrency Yes Yes Yes Global Yes
innodb_compression_failure_threshold_pct Yes Yes Yes Global Yes
innodb_compression_level Yes Yes Yes Global Yes
innodb_compression_pad_pct_max Yes Yes Yes Global Yes
innodb_concurrency_tickets Yes Yes Yes Global Yes
innodb_data_file_path Yes Yes Yes Global No
Innodb_data_fsyncs Yes Global No
innodb_data_home_dir Yes Yes Yes Global No
Innodb_data_pending_fsyncs Yes Global No
Innodb_data_pending_reads Yes Global No
Innodb_data_pending_writes Yes Global No
Innodb_data_read Yes Global No
Innodb_data_reads Yes Global No
Innodb_data_writes Yes Global No
Innodb_data_written Yes Global No
Innodb_dblwr_pages_written Yes Global No
Innodb_dblwr_writes Yes Global No
innodb_disable_sort_file_cache Yes Yes Yes Global Yes
innodb_doublewrite Yes Yes Yes Global No
innodb_fast_shutdown Yes Yes Yes Global Yes
innodb_fil_make_page_dirty_debug Yes Yes Yes Global Yes
innodb_file_format Yes Yes Yes Global Yes
innodb_file_format_check Yes Yes Yes Global No
innodb_file_format_max Yes Yes Yes Global Yes
innodb_file_per_table Yes Yes Yes Global Yes
innodb_flush_log_at_timeout Yes Global Yes
innodb_flush_log_at_trx_commit Yes Yes Yes Global Yes
innodb_flush_method Yes Yes Yes Global No
innodb_flush_neighbors Yes Yes Yes Global Yes
innodb_flushing_avg_loops Yes Yes Yes Global Yes
innodb_force_load_corrupted Yes Yes Yes Global No
innodb_force_recovery Yes Yes Yes Global No
innodb_ft_aux_table Yes Global Yes
innodb_ft_cache_size Yes Yes Yes Global No
innodb_ft_enable_diag_print Yes Yes Yes Global Yes
innodb_ft_enable_stopword Yes Yes Yes Both Yes
innodb_ft_max_token_size Yes Yes Yes Global No
innodb_ft_min_token_size Yes Yes Yes Global No
innodb_ft_num_word_optimize Yes Yes Yes Global Yes
innodb_ft_result_cache_limit Yes Yes Yes Global Yes
innodb_ft_server_stopword_table Yes Yes Yes Global Yes
innodb_ft_sort_pll_degree Yes Yes Yes Global No
innodb_ft_total_cache_size Yes Yes Yes Global No
innodb_ft_user_stopword_table Yes Yes Yes Both Yes
Innodb_have_atomic_builtins Yes Global No
innodb_io_capacity Yes Yes Yes Global Yes
innodb_io_capacity_max Yes Yes Yes Global Yes
innodb_large_prefix Yes Yes Yes Global Yes
innodb_limit_optimistic_insert_debug Yes Yes Yes Global Yes
innodb_lock_wait_timeout Yes Yes Yes Both Yes
innodb_locks_unsafe_for_binlog Yes Yes Yes Global No
innodb_log_buffer_size Yes Yes Yes Global No
innodb_log_checkpoint_now Yes Yes Yes Global Yes
innodb_log_compressed_pages Yes Yes Yes Global Yes
innodb_log_file_size Yes Yes Yes Global No
innodb_log_files_in_group Yes Yes Yes Global No
innodb_log_group_home_dir Yes Yes Yes Global No
Innodb_log_waits Yes Global No
Innodb_log_write_requests Yes Global No
Innodb_log_writes Yes Global No
innodb_lru_scan_depth Yes Yes Yes Global Yes
innodb_max_dirty_pages_pct Yes Yes Yes Global Yes
innodb_max_dirty_pages_pct_lwm Yes Yes Yes Global Yes
innodb_max_purge_lag Yes Yes Yes Global Yes
innodb_max_purge_lag_delay Yes Yes Yes Global Yes
innodb_mirrored_log_groups Yes Yes Yes Global No
innodb_monitor_disable Yes Yes Yes Global Yes
innodb_monitor_enable Yes Yes Yes Global Yes
innodb_monitor_reset Yes Yes Yes Global Yes
innodb_monitor_reset_all Yes Yes Yes Global Yes
Innodb_num_open_files Yes Global No
innodb_numa_interleave Yes Yes Yes Global No
innodb_old_blocks_pct Yes Yes Yes Global Yes
innodb_old_blocks_time Yes Yes Yes Global Yes
innodb_online_alter_log_max_size Yes Yes Yes Global Yes
innodb_open_files Yes Yes Yes Global No
innodb_optimize_fulltext_only Yes Yes Yes Global Yes
Innodb_os_log_fsyncs Yes Global No
Innodb_os_log_pending_fsyncs Yes Global No
Innodb_os_log_pending_writes Yes Global No
Innodb_os_log_written Yes Global No
Innodb_page_size Yes Global No
innodb_page_size Yes Yes Yes Global No
Innodb_pages_created Yes Global No
Innodb_pages_read Yes Global No
Innodb_pages_written Yes Global No
innodb_print_all_deadlocks Yes Yes Yes Global Yes
innodb_purge_batch_size Yes Yes Yes Global Yes
innodb_purge_threads Yes Yes Yes Global No
innodb_random_read_ahead Yes Yes Yes Global Yes
innodb_read_ahead_threshold Yes Yes Yes Global Yes
innodb_read_io_threads Yes Yes Yes Global No
innodb_read_only Yes Yes Yes Global No
innodb_replication_delay Yes Yes Yes Global Yes
innodb_rollback_on_timeout Yes Yes Yes Global No
innodb_rollback_segments Yes Yes Yes Global Yes
Innodb_row_lock_current_waits Yes Global No
Innodb_row_lock_time Yes Global No
Innodb_row_lock_time_avg Yes Global No
Innodb_row_lock_time_max Yes Global No
Innodb_row_lock_waits Yes Global No
Innodb_rows_deleted Yes Global No
Innodb_rows_inserted Yes Global No
Innodb_rows_read Yes Global No
Innodb_rows_updated Yes Global No
innodb_saved_page_number_debug Yes Yes Yes Global Yes
innodb_sort_buffer_size Yes Yes Yes Global No
innodb_spin_wait_delay Yes Yes Yes Global Yes
innodb_stats_auto_recalc Yes Yes Yes Global Yes
innodb_stats_include_delete_marked Yes Yes Yes Global Yes
innodb_stats_method Yes Yes Yes Global Yes
innodb_stats_on_metadata Yes Yes Yes Global Yes
innodb_stats_persistent Yes Yes Yes Global Yes
innodb_stats_persistent_sample_pages Yes Yes Yes Global Yes
innodb_stats_sample_pages Yes Yes Yes Global Yes
innodb_stats_transient_sample_pages Yes Yes Yes Global Yes
innodb-status-file Yes Yes
innodb_status_output Yes Yes Yes Global Yes
innodb_status_output_locks Yes Yes Yes Global Yes
innodb_strict_mode Yes Yes Yes Both Yes
innodb_support_xa Yes Yes Yes Both Yes
innodb_sync_array_size Yes Yes Yes Global No
innodb_sync_spin_loops Yes Yes Yes Global Yes
innodb_table_locks Yes Yes Yes Both Yes
innodb_thread_concurrency Yes Yes Yes Global Yes
innodb_thread_sleep_delay Yes Yes Yes Global Yes
innodb_tmpdir Yes Yes Yes Both Yes
Innodb_truncated_status_writes Yes Global No
innodb_trx_purge_view_update_only_debug Yes Yes Yes Global Yes
innodb_trx_rseg_n_slots_debug Yes Yes Yes Global Yes
innodb_undo_directory Yes Yes Yes Global No
innodb_undo_logs Yes Yes Yes Global Yes
innodb_undo_tablespaces Yes Yes Yes Global No
innodb_use_native_aio Yes Yes Yes Global No
innodb_use_sys_malloc Yes Yes Yes Global No
innodb_version Yes Global No
innodb_write_io_threads Yes Yes Yes Global No
insert_id Yes Session Yes
install Yes
install-manual Yes
interactive_timeout Yes Yes Yes Both Yes
join_buffer_size Yes Yes Yes Both Yes
keep_files_on_create Yes Yes Yes Both Yes
Key_blocks_not_flushed Yes Global No
Key_blocks_unused Yes Global No
Key_blocks_used Yes Global No
key_buffer_size Yes Yes Yes Global Yes
key_cache_age_threshold Yes Yes Yes Global Yes
key_cache_block_size Yes Yes Yes Global Yes
key_cache_division_limit Yes Yes Yes Global Yes
Key_read_requests Yes Global No
Key_reads Yes Global No
Key_write_requests Yes Global No
Key_writes Yes Global No
language Yes Yes Yes Global No
large_files_support Yes Global No
large_page_size Yes Global No
large-pages Yes Yes Global No
- Variable: large_pages Yes Global No
last_insert_id Yes Session Yes
Last_query_cost Yes Session No
Last_query_partial_plans Yes Session No
lc-messages Yes Yes Both Yes
- Variable: lc_messages Yes Both Yes
lc-messages-dir Yes Yes Global No
- Variable: lc_messages_dir Yes Global No
lc_time_names Yes Both Yes
license Yes Global No
local_infile Yes Global Yes
local-service Yes
lock_wait_timeout Yes Yes Yes Both Yes
locked_in_memory Yes Global No
log Yes Yes Yes Global Yes
log-bin Yes Yes Yes Global No
log_bin Yes Global No
log_bin_basename Yes Global No
log-bin-index Yes Yes
log_bin_index Yes Global No
log-bin-trust-function-creators Yes Yes Global Yes
- Variable: log_bin_trust_function_creators Yes Global Yes
log-bin-use-v1-row-events Yes Yes Global No
- Variable: log_bin_use_v1_row_events Yes Global No
log_bin_use_v1_row_events Yes Yes Yes Global No
log-error Yes Yes Global No
- Variable: log_error Yes Global No
log-isam Yes Yes
log_output Yes Yes Yes Global Yes
log-queries-not-using-indexes Yes Yes Global Yes
- Variable: log_queries_not_using_indexes Yes Global Yes
log-raw Yes Yes
log-short-format Yes Yes
log-slave-updates Yes Yes Global No
- Variable: log_slave_updates Yes Global No
log_slave_updates Yes Yes Yes Global No
log-slow-admin-statements Yes Yes
log_slow_admin_statements Yes Global Yes
log-slow-queries Yes Yes Global Yes
- Variable: log_slow_queries Yes Global Yes
log-slow-slave-statements Yes Yes
log_slow_slave_statements Yes Global Yes
log-tc Yes Yes
log-tc-size Yes Yes
log_throttle_queries_not_using_indexes Yes Global Yes
log-warnings Yes Yes Varies Yes
- Variable: log_warnings Yes Varies Yes
long_query_time Yes Yes Yes Both Yes
low-priority-updates Yes Yes Both Yes
- Variable: low_priority_updates Yes Both Yes
lower_case_file_system Yes Global No
lower_case_table_names Yes Yes Yes Global No
master-info-file Yes Yes
master-info-repository Yes Yes
- Variable: master_info_repository
master_info_repository Yes Yes Yes Global Yes
master-retry-count Yes Yes
master-verify-checksum Yes Yes
- Variable: master_verify_checksum
master_verify_checksum Yes Global Yes
max_allowed_packet Yes Yes Yes Both Yes
max_binlog_cache_size Yes Yes Yes Global Yes
max-binlog-dump-events Yes Yes
max_binlog_size Yes Yes Yes Global Yes
max_binlog_stmt_cache_size Yes Yes Yes Global Yes
max_connect_errors Yes Yes Yes Global Yes
max_connections Yes Yes Yes Global Yes
max_delayed_threads Yes Yes Yes Both Yes
max_digest_length Yes Yes Yes Global No
max_error_count Yes Yes Yes Both Yes
max_heap_table_size Yes Yes Yes Both Yes
max_insert_delayed_threads Yes Both Yes
max_join_size Yes Yes Yes Both Yes
max_length_for_sort_data Yes Yes Yes Both Yes
max_prepared_stmt_count Yes Yes Yes Global Yes
max_relay_log_size Yes Yes Yes Global Yes
max_seeks_for_key Yes Yes Yes Both Yes
max_sort_length Yes Yes Yes Both Yes
max_sp_recursion_depth Yes Yes Yes Both Yes
max_tmp_tables Yes Both Yes
Max_used_connections Yes Global No
max_user_connections Yes Yes Yes Both Yes
max_write_lock_count Yes Yes Yes Global Yes
memlock Yes Yes
- Variable: locked_in_memory
metadata_locks_cache_size Yes Global No
metadata_locks_hash_instances Yes Global No
min-examined-row-limit Yes Yes Yes Both Yes
multi_range_count Yes Yes Yes Both Yes
myisam-block-size Yes Yes
myisam_data_pointer_size Yes Yes Yes Global Yes
myisam_max_sort_file_size Yes Yes Yes Global Yes
myisam_mmap_size Yes Yes Yes Global No
myisam-recover-options Yes Yes
- Variable: myisam_recover_options
myisam_recover_options Yes Global No
myisam_repair_threads Yes Yes Yes Both Yes
myisam_sort_buffer_size Yes Yes Yes Both Yes
myisam_stats_method Yes Yes Yes Both Yes
myisam_use_mmap Yes Yes Yes Global Yes
mysql_firewall_max_query_size Yes Yes Yes Global No
mysql_firewall_mode Yes Yes Yes Global Yes
mysql_firewall_trace Yes Yes Yes Global Yes
named_pipe Yes Global No
Ndb_api_bytes_received_count Yes Global No
Ndb_api_bytes_received_count_session Yes Session No
Ndb_api_bytes_received_count_slave Yes Global No
Ndb_api_bytes_sent_count Yes Global No
Ndb_api_bytes_sent_count_session Yes Session No
Ndb_api_bytes_sent_count_slave Yes Global No
Ndb_api_event_bytes_count Yes Global No
Ndb_api_event_bytes_count_injector Yes Global No
Ndb_api_event_data_count Yes Global No
Ndb_api_event_data_count_injector Yes Global No
Ndb_api_event_nondata_count Yes Global No
Ndb_api_event_nondata_count_injector Yes Global No
Ndb_api_pk_op_count Yes Global No
Ndb_api_pk_op_count_session Yes Session No
Ndb_api_pk_op_count_slave Yes Global No
Ndb_api_pruned_scan_count Yes Global No
Ndb_api_pruned_scan_count_session Yes Session No
Ndb_api_pruned_scan_count_slave Yes Global No
Ndb_api_range_scan_count Yes Global No
Ndb_api_range_scan_count_session Yes Session No
Ndb_api_range_scan_count_slave Yes Global No
Ndb_api_read_row_count Yes Global No
Ndb_api_read_row_count_session Yes Session No
Ndb_api_read_row_count_slave Yes Global No
Ndb_api_scan_batch_count Yes Global No
Ndb_api_scan_batch_count_session Yes Session No
Ndb_api_scan_batch_count_slave Yes Global No
Ndb_api_table_scan_count Yes Global No
Ndb_api_table_scan_count_session Yes Session No
Ndb_api_table_scan_count_slave Yes Global No
Ndb_api_trans_abort_count Yes Global No
Ndb_api_trans_abort_count_session Yes Session No
Ndb_api_trans_abort_count_slave Yes Global No
Ndb_api_trans_close_count Yes Global No
Ndb_api_trans_close_count_session Yes Session No
Ndb_api_trans_close_count_slave Yes Global No
Ndb_api_trans_commit_count Yes Global No
Ndb_api_trans_commit_count_session Yes Session No
Ndb_api_trans_commit_count_slave Yes Global No
Ndb_api_trans_local_read_row_count Yes Global No
Ndb_api_trans_local_read_row_count_session Yes Session No
Ndb_api_trans_local_read_row_count_slave Yes Global No
Ndb_api_trans_start_count Yes Global No
Ndb_api_trans_start_count_session Yes Session No
Ndb_api_trans_start_count_slave Yes Global No
Ndb_api_uk_op_count Yes Global No
Ndb_api_uk_op_count_session Yes Session No
Ndb_api_uk_op_count_slave Yes Global No
Ndb_api_wait_exec_complete_count Yes Global No
Ndb_api_wait_exec_complete_count_session Yes Session No
Ndb_api_wait_exec_complete_count_slave Yes Global No
Ndb_api_wait_meta_request_count Yes Global No
Ndb_api_wait_meta_request_count_session Yes Session No
Ndb_api_wait_meta_request_count_slave Yes Global No
Ndb_api_wait_nanos_count Yes Global No
Ndb_api_wait_nanos_count_session Yes Session No
Ndb_api_wait_nanos_count_slave Yes Global No
Ndb_api_wait_scan_result_count Yes Global No
Ndb_api_wait_scan_result_count_session Yes Session No
Ndb_api_wait_scan_result_count_slave Yes Global No
ndb_autoincrement_prefetch_sz Yes Yes Yes Both Yes
ndb-batch-size Yes Yes Yes Global No
ndb-blob-read-batch-bytes Yes Yes Yes Both Yes
ndb-blob-write-batch-bytes Yes Yes Yes Both Yes
ndb_cache_check_time Yes Yes Yes Global Yes
ndb_clear_apply_status Yes Yes Global Yes
ndb-cluster-connection-pool Yes Yes Yes Global No
Ndb_cluster_node_id Yes Both No
Ndb_config_from_host Yes Both No
Ndb_config_from_port Yes Both No
Ndb_conflict_fn_epoch Yes Global No
Ndb_conflict_fn_epoch_trans Yes Global No
Ndb_conflict_fn_epoch2 Yes Global No
Ndb_conflict_fn_epoch2_trans Yes Global No
Ndb_conflict_fn_max Yes Global No
Ndb_conflict_fn_max_del_win Yes Global No
Ndb_conflict_fn_old Yes Global No
Ndb_conflict_last_conflict_epoch Yes Global No
Ndb_conflict_last_stable_epoch Yes Global No
Ndb_conflict_reflected_op_discard_count Yes Global No
Ndb_conflict_reflected_op_prepare_count Yes Global No
Ndb_conflict_refresh_op_count Yes Global No
Ndb_conflict_trans_conflict_commit_count Yes Global No
Ndb_conflict_trans_detect_iter_count Yes Global No
Ndb_conflict_trans_reject_count Yes Global No
Ndb_conflict_trans_row_conflict_count Yes Global No
Ndb_conflict_trans_row_reject_count Yes Global No
ndb-connectstring Yes Yes
ndb-deferred-constraints Yes Yes Both Yes
- Variable: ndb_deferred_constraints Yes Both Yes
ndb_deferred_constraints Yes Yes Yes Both Yes
ndb-distribution Yes Yes Global Yes
- Variable: ndb_distribution Yes Global Yes
ndb_distribution Yes Yes Yes Global Yes
Ndb_epoch_delete_delete_count Yes Global No
ndb_eventbuffer_free_percent Yes Yes Yes Global Yes
ndb_eventbuffer_max_alloc Yes Yes Yes Global Yes
Ndb_execute_count Yes Global No
ndb_extra_logging Yes Yes Yes Global Yes
ndb_force_send Yes Yes Yes Both Yes
ndb_index_stat_cache_entries Yes Yes Yes Both Yes
ndb_index_stat_enable Yes Yes Yes Both Yes
ndb_index_stat_option Yes Yes Yes Both Yes
ndb_index_stat_update_freq Yes Yes Yes Both Yes
ndb_join_pushdown Yes Both Yes
Ndb_last_commit_epoch_server Yes Global No
Ndb_last_commit_epoch_session Yes Session No
ndb-log-apply-status Yes Yes Global No
- Variable: ndb_log_apply_status Yes Global No
ndb_log_apply_status Yes Yes Yes Global No
ndb_log_bin Yes Yes Both Yes
ndb_log_binlog_index Yes Yes Global Yes
ndb-log-empty-epochs Yes Yes Yes Global Yes
ndb_log_empty_epochs Yes Yes Yes Global Yes
ndb-log-empty-update Yes Yes Yes Global Yes
ndb_log_empty_update Yes Yes Yes Global Yes
ndb-log-exclusive-reads Yes Yes Both Yes
- Variable: ndb_log_exclusive_reads Yes Both Yes
ndb_log_exclusive_reads Yes Yes Yes Both Yes
ndb-log-orig Yes Yes Global No
- Variable: ndb_log_orig Yes Global No
ndb_log_orig Yes Yes Yes Global No
ndb-log-transaction-id Yes Yes Global No
- Variable: ndb_log_transaction_id Yes Global No
ndb_log_transaction_id Yes Global No
ndb-log-update-as-write Yes Yes Yes Global Yes
ndb-log-update-minimal Yes Yes Yes Global Yes
ndb_log_updated_only Yes Yes Yes Global Yes
ndb-mgmd-host Yes Yes
ndb-nodeid Yes Yes Yes Global No
Ndb_number_of_data_nodes Yes Global No
ndb_optimization_delay Yes Global Yes
ndb_optimized_node_selection Yes Yes Yes Global No
Ndb_pruned_scan_count Yes Global No
Ndb_pushed_queries_defined Yes Global No
Ndb_pushed_queries_dropped Yes Global No
Ndb_pushed_queries_executed Yes Global No
Ndb_pushed_reads Yes Global No
ndb-recv-thread-activation-threshold Yes Yes
- Variable: ndb_recv_thread_activation_threshold
ndb_recv_thread_activation_threshold Yes Global Yes
ndb-recv-thread-cpu-mask Yes Yes
- Variable: ndb_recv_thread_cpu_mask
ndb_recv_thread_cpu_mask Yes Global Yes
ndb_report_thresh_binlog_epoch_slip Yes Yes Yes Global Yes
ndb_report_thresh_binlog_mem_usage Yes Yes Yes Global Yes
Ndb_scan_count Yes Global No
ndb_show_foreign_key_mock_tables Yes Yes Yes Global Yes
ndb_slave_conflict_role Yes Yes Yes Global Yes
Ndb_slave_max_replicated_epoch Yes Global No
ndb_table_no_logging Yes Session Yes
ndb_table_temporary Yes Session Yes
ndb-transid-mysql-connection-map Yes
ndb_use_copying_alter_table Yes Both No
ndb_use_exact_count Yes Both Yes
ndb_use_transactions Yes Yes Yes Both Yes
ndb_version Yes Global No
ndb_version_string Yes Global No
ndb-wait-connected Yes Yes Yes Global No
ndb-wait-setup Yes Yes Yes Global No
ndbcluster Yes Yes
- Variable: have_ndbcluster
ndbinfo_database Yes Global No
ndbinfo_max_bytes Yes Yes Both Yes
ndbinfo_max_rows Yes Yes Both Yes
ndbinfo_offline Yes Global Yes
ndbinfo_show_hidden Yes Yes Both Yes
ndbinfo_table_prefix Yes Yes Both Yes
ndbinfo_version Yes Global No
net_buffer_length Yes Yes Yes Both Yes
net_read_timeout Yes Yes Yes Both Yes
net_retry_count Yes Yes Yes Both Yes
net_write_timeout Yes Yes Yes Both Yes
new Yes Yes Yes Both Yes
no-defaults Yes
Not_flushed_delayed_rows Yes Global No
old Yes Yes Yes Global No
old-alter-table Yes Yes Both Yes
- Variable: old_alter_table Yes Both Yes
old_passwords Yes Both Yes
old-style-user-limits Yes Yes
one-thread Yes Yes
Open_files Yes Global No
open-files-limit Yes Yes Global No
- Variable: open_files_limit Yes Global No
Open_streams Yes Global No
Open_table_definitions Yes Global No
Open_tables Yes Both No
Opened_files Yes Global No
Opened_table_definitions Yes Both No
Opened_tables Yes Both No
optimizer_join_cache_level Yes Yes Yes Both Yes
optimizer_prune_level Yes Yes Yes Both Yes
optimizer_search_depth Yes Yes Yes Both Yes
optimizer_switch Yes Yes Yes Both Yes
optimizer_trace Yes Both Yes
optimizer_trace_features Yes Both Yes
optimizer_trace_limit Yes Both Yes
optimizer_trace_max_mem_size Yes Both Yes
optimizer_trace_offset Yes Both Yes
partition Yes Yes
- Variable: have_partitioning
performance_schema Yes Yes Yes Global No
Performance_schema_accounts_lost Yes Global No
performance_schema_accounts_size Yes Yes Yes Global No
Performance_schema_cond_classes_lost Yes Global No
Performance_schema_cond_instances_lost Yes Global No
performance-schema-consumer-events-stages-current Yes Yes
performance-schema-consumer-events-stages-history Yes Yes
performance-schema-consumer-events-stages-history-long Yes Yes
performance-schema-consumer-events-statements-current Yes Yes
performance-schema-consumer-events-statements-history Yes Yes
performance-schema-consumer-events-statements-history-long Yes Yes
performance-schema-consumer-events-waits-current Yes Yes
performance-schema-consumer-events-waits-history Yes Yes
performance-schema-consumer-events-waits-history-long Yes Yes
performance-schema-consumer-global-instrumentation Yes Yes
performance-schema-consumer-statements-digest Yes Yes
performance-schema-consumer-thread-instrumentation Yes Yes
Performance_schema_digest_lost Yes Global No
performance_schema_digests_size Yes Yes Yes Global No
performance_schema_events_stages_history_long_size Yes Yes Yes Global No
performance_schema_events_stages_history_size Yes Yes Yes Global No
performance_schema_events_statements_history_long_size Yes Yes Yes Global No
performance_schema_events_statements_history_size Yes Yes Yes Global No
performance_schema_events_waits_history_long_size Yes Yes Yes Global No
performance_schema_events_waits_history_size Yes Yes Yes Global No
Performance_schema_file_classes_lost Yes Global No
Performance_schema_file_handles_lost Yes Global No
Performance_schema_file_instances_lost Yes Global No
Performance_schema_hosts_lost Yes Global No
performance_schema_hosts_size Yes Yes Yes Global No
performance-schema-instrument Yes Yes
Performance_schema_locker_lost Yes Global No
performance_schema_max_cond_classes Yes Yes Yes Global No
performance_schema_max_cond_instances Yes Yes Yes Global No
performance_schema_max_digest_length Yes Yes Yes Global No
performance_schema_max_file_classes Yes Yes Yes Global No
performance_schema_max_file_handles Yes Yes Yes Global No
performance_schema_max_file_instances Yes Yes Yes Global No
performance_schema_max_mutex_classes Yes Yes Yes Global No
performance_schema_max_mutex_instances Yes Yes Yes Global No
performance_schema_max_rwlock_classes Yes Yes Yes Global No
performance_schema_max_rwlock_instances Yes Yes Yes Global No
performance_schema_max_socket_classes Yes Yes Yes Global No
performance_schema_max_socket_instances Yes Yes Yes Global No
performance_schema_max_stage_classes Yes Yes Yes Global No
performance_schema_max_statement_classes Yes Yes Yes Global No
performance_schema_max_table_handles Yes Yes Yes Global No
performance_schema_max_table_instances Yes Yes Yes Global No
performance_schema_max_thread_classes Yes Yes Yes Global No
performance_schema_max_thread_instances Yes Yes Yes Global No
Performance_schema_mutex_classes_lost Yes Global No
Performance_schema_mutex_instances_lost Yes Global No
Performance_schema_rwlock_classes_lost Yes Global No
Performance_schema_rwlock_instances_lost Yes Global No
Performance_schema_session_connect_attrs_lost Yes Global No
performance_schema_session_connect_attrs_size Yes Yes Yes Global No
performance_schema_setup_actors_size Yes Yes Yes Global No
performance_schema_setup_objects_size Yes Yes Yes Global No
Performance_schema_socket_classes_lost Yes Global No
Performance_schema_socket_instances_lost Yes Global No
Performance_schema_stage_classes_lost Yes Global No
Performance_schema_statement_classes_lost Yes Global No
Performance_schema_table_handles_lost Yes Global No
Performance_schema_table_instances_lost Yes Global No
Performance_schema_thread_classes_lost Yes Global No
Performance_schema_thread_instances_lost Yes Global No
Performance_schema_users_lost Yes Global No
performance_schema_users_size Yes Yes Yes Global No
pid-file Yes Yes Global No
- Variable: pid_file Yes Global No
plugin Yes Yes
plugin_dir Yes Yes Yes Global No
plugin-load Yes Yes
plugin-load-add Yes Yes
port Yes Yes Yes Global No
port-open-timeout Yes Yes
preload_buffer_size Yes Yes Yes Both Yes
Prepared_stmt_count Yes Global No
print-defaults Yes
profiling Yes Both Yes
profiling_history_size Yes Yes Yes Both Yes
protocol_version Yes Global No
proxy_user Yes Session No
pseudo_slave_mode Yes Session Yes
pseudo_thread_id Yes Session Yes
Qcache_free_blocks Yes Global No
Qcache_free_memory Yes Global No
Qcache_hits Yes Global No
Qcache_inserts Yes Global No
Qcache_lowmem_prunes Yes Global No
Qcache_not_cached Yes Global No
Qcache_queries_in_cache Yes Global No
Qcache_total_blocks Yes Global No
Queries Yes Both No
query_alloc_block_size Yes Yes Yes Both Yes
query_cache_limit Yes Yes Yes Global Yes
query_cache_min_res_unit Yes Yes Yes Global Yes
query_cache_size Yes Yes Yes Global Yes
query_cache_type Yes Yes Yes Both Yes
query_cache_wlock_invalidate Yes Yes Yes Both Yes
query_prealloc_size Yes Yes Yes Both Yes
Questions Yes Both No
rand_seed1 Yes Session Yes
rand_seed2 Yes Session Yes
range_alloc_block_size Yes Yes Yes Both Yes
read_buffer_size Yes Yes Yes Both Yes
read_only Yes Yes Yes Global Yes
read_rnd_buffer_size Yes Yes Yes Both Yes
relay-log Yes Yes Global No
- Variable: relay_log Yes Global No
relay_log_basename Yes Global No
relay-log-index Yes Yes Global No
- Variable: relay_log_index Yes Global No
relay_log_index Yes Yes Yes Global No
relay-log-info-file Yes Yes
- Variable: relay_log_info_file
relay_log_info_file Yes Yes Yes Global No
relay-log-info-repository Yes Yes
- Variable: relay_log_info_repository
relay_log_info_repository Yes Global Yes
relay_log_purge Yes Yes Yes Global Yes
relay-log-recovery Yes Yes
- Variable: relay_log_recovery
relay_log_recovery Yes Yes Yes Global Varies
relay_log_space_limit Yes Yes Yes Global No
remove Yes
replicate-do-db Yes Yes
replicate-do-table Yes Yes
replicate-ignore-db Yes Yes
replicate-ignore-table Yes Yes
replicate-rewrite-db Yes Yes
replicate-same-server-id Yes Yes
replicate-wild-do-table Yes Yes
replicate-wild-ignore-table Yes Yes
report-host Yes Yes Global No
- Variable: report_host Yes Global No
report-password Yes Yes Global No
- Variable: report_password Yes Global No
report-port Yes Yes Global No
- Variable: report_port Yes Global No
report-user Yes Yes Global No
- Variable: report_user Yes Global No
Rpl_semi_sync_master_clients Yes Global No
rpl_semi_sync_master_enabled Yes Global Yes
Rpl_semi_sync_master_net_avg_wait_time Yes Global No
Rpl_semi_sync_master_net_wait_time Yes Global No
Rpl_semi_sync_master_net_waits Yes Global No
Rpl_semi_sync_master_no_times Yes Global No
Rpl_semi_sync_master_no_tx Yes Global No
Rpl_semi_sync_master_status Yes Global No
Rpl_semi_sync_master_timefunc_failures Yes Global No
rpl_semi_sync_master_timeout Yes Global Yes
rpl_semi_sync_master_trace_level Yes Global Yes
Rpl_semi_sync_master_tx_avg_wait_time Yes Global No
Rpl_semi_sync_master_tx_wait_time Yes Global No
Rpl_semi_sync_master_tx_waits Yes Global No
rpl_semi_sync_master_wait_no_slave Yes Global Yes
Rpl_semi_sync_master_wait_pos_backtraverse Yes Global No
Rpl_semi_sync_master_wait_sessions Yes Global No
Rpl_semi_sync_master_yes_tx Yes Global No
rpl_semi_sync_slave_enabled Yes Global Yes
Rpl_semi_sync_slave_status Yes Global No
rpl_semi_sync_slave_trace_level Yes Global Yes
rpl_stop_slave_timeout Yes Yes Yes Global Yes
Rsa_public_key Yes Global No
safe-mode Yes Yes
safe-user-create Yes Yes
secure-auth Yes Yes Global Yes
- Variable: secure_auth Yes Global Yes
secure-file-priv Yes Yes Global No
- Variable: secure_file_priv Yes Global No
Select_full_join Yes Both No
Select_full_range_join Yes Both No
Select_range Yes Both No
Select_range_check Yes Both No
Select_scan Yes Both No
server-id Yes Yes Global Yes
- Variable: server_id Yes Global Yes
server-id-bits Yes Yes Global No
- Variable: server_id_bits Yes Global No
server_id_bits Yes Yes Yes Global No
server_uuid Yes Global No
sha256_password_private_key_path Yes Yes Yes Global No
sha256_password_public_key_path Yes Yes Yes Global No
shared_memory Yes Yes Yes Global No
shared_memory_base_name Yes Yes Yes Global No
show_old_temporals Yes Yes Yes Both Yes
show-slave-auth-info Yes Yes
simplified_binlog_gtid_recovery Yes Yes Yes Global No
skip-character-set-client-handshake Yes Yes
skip-concurrent-insert Yes Yes
- Variable: concurrent_insert
skip-event-scheduler Yes Yes
skip_external_locking Yes Yes Yes Global No
skip-grant-tables Yes Yes
skip-host-cache Yes Yes
skip-name-resolve Yes Yes Global No
- Variable: skip_name_resolve Yes Global No
skip-ndbcluster Yes Yes
skip-networking Yes Yes Global No
- Variable: skip_networking Yes Global No
skip-new Yes Yes
skip-partition Yes Yes
skip-show-database Yes Yes Global No
- Variable: skip_show_database Yes Global No
skip-slave-start Yes Yes
skip-ssl Yes Yes
skip-stack-trace Yes Yes
skip-thread-priority Yes Yes
slave_allow_batching Yes Yes Yes Global Yes
slave-checkpoint-group Yes Yes
- Variable: slave_checkpoint_group
slave_checkpoint_group Yes Yes Yes Global Yes
slave-checkpoint-period Yes Yes
- Variable: slave_checkpoint_period
slave_checkpoint_period Yes Yes Yes Global Yes
slave_compressed_protocol Yes Yes Yes Global Yes
slave_exec_mode Yes Yes Yes Global Yes
Slave_heartbeat_period Yes Global No
Slave_last_heartbeat Yes Global No
slave-load-tmpdir Yes Yes Global No
- Variable: slave_load_tmpdir Yes Global No
slave-max-allowed-packet Yes Yes
- Variable: slave_max_allowed_packet
slave_max_allowed_packet Yes Global Yes
slave-net-timeout Yes Yes Global Yes
- Variable: slave_net_timeout Yes Global Yes
Slave_open_temp_tables Yes Global No
slave-parallel-workers Yes Yes
- Variable: slave_parallel_workers
slave_parallel_workers Yes Yes Global Yes
slave-pending-jobs-size-max Yes
- Variable: slave_pending_jobs_size_max
slave_pending_jobs_size_max Yes Yes Global Yes
Slave_received_heartbeats Yes Global No
Slave_retried_transactions Yes Global No
Slave_rows_last_search_algorithm_used Yes Global No
slave-rows-search-algorithms Yes Yes
- Variable: slave_rows_search_algorithms
slave_rows_search_algorithms Yes Global Yes
Slave_running Yes Global No
slave-skip-errors Yes Yes Global No
- Variable: slave_skip_errors Yes Global No
slave-sql-verify-checksum Yes Yes
slave_sql_verify_checksum Yes Global Yes
slave_transaction_retries Yes Yes Yes Global Yes
slave_type_conversions Yes Yes Yes Global No
Slow_launch_threads Yes Both No
slow_launch_time Yes Yes Yes Global Yes
Slow_queries Yes Both No
slow-query-log Yes Yes Global Yes
- Variable: slow_query_log Yes Global Yes
slow_query_log_file Yes Yes Yes Global Yes
slow-start-timeout Yes Yes
socket Yes Yes Yes Global No
sort_buffer_size Yes Yes Yes Both Yes
Sort_merge_passes Yes Both No
Sort_range Yes Both No
Sort_rows Yes Both No
Sort_scan Yes Both No
sporadic-binlog-dump-fail Yes Yes
sql_auto_is_null Yes Both Yes
sql_big_selects Yes Both Yes
sql_big_tables Yes Both Yes
sql_buffer_result Yes Both Yes
sql_log_bin Yes Session Yes
sql_log_off Yes Both Yes
sql_low_priority_updates Yes Both Yes
sql_max_join_size Yes Both Yes
sql-mode Yes Yes Both Yes
- Variable: sql_mode Yes Both Yes
sql_notes Yes Both Yes
sql_quote_show_create Yes Both Yes
sql_safe_updates Yes Both Yes
sql_select_limit Yes Both Yes
sql_slave_skip_counter Yes Global Yes
sql_warnings Yes Both Yes
ssl Yes Yes
Ssl_accept_renegotiates Yes Global No
Ssl_accepts Yes Global No
ssl-ca Yes Yes Global No
- Variable: ssl_ca Yes Global No
Ssl_callback_cache_hits Yes Global No
ssl-capath Yes Yes Global No
- Variable: ssl_capath Yes Global No
ssl-cert Yes Yes Global No
- Variable: ssl_cert Yes Global No
Ssl_cipher Yes Both No
ssl-cipher Yes Yes Global No
- Variable: ssl_cipher Yes Global No
Ssl_cipher_list Yes Both No
Ssl_client_connects Yes Global No
Ssl_connect_renegotiates Yes Global No
ssl-crl Yes Yes Global No
- Variable: ssl_crl Yes Global No
ssl-crlpath Yes Yes Global No
- Variable: ssl_crlpath Yes Global No
Ssl_ctx_verify_depth Yes Global No
Ssl_ctx_verify_mode Yes Global No
Ssl_default_timeout Yes Both No
Ssl_finished_accepts Yes Global No
Ssl_finished_connects Yes Global No
ssl-key Yes Yes Global No
- Variable: ssl_key Yes Global No
Ssl_server_not_after Yes Both No
Ssl_server_not_before Yes Both No
Ssl_session_cache_hits Yes Global No
Ssl_session_cache_misses Yes Global No
Ssl_session_cache_mode Yes Global No
Ssl_session_cache_overflows Yes Global No
Ssl_session_cache_size Yes Global No
Ssl_session_cache_timeouts Yes Global No
Ssl_sessions_reused Yes Both No
Ssl_used_session_cache_entries Yes Global No
Ssl_verify_depth Yes Both No
Ssl_verify_mode Yes Both No
Ssl_version Yes Both No
standalone Yes Yes
storage_engine Yes Both Yes
stored_program_cache Yes Yes Yes Global Yes
super-large-pages Yes Yes
symbolic-links Yes Yes
sync_binlog Yes Yes Yes Global Yes
sync_frm Yes Yes Yes Global Yes
sync_master_info Yes Yes Yes Global Yes
sync_relay_log Yes Yes Yes Global Yes
sync_relay_log_info Yes Yes Yes Global Yes
sysdate-is-now Yes Yes
system_time_zone Yes Global No
table_definition_cache Yes Global Yes
Table_locks_immediate Yes Global No
Table_locks_waited Yes Global No
table_open_cache Yes Global Yes
Table_open_cache_hits Yes Both No
table_open_cache_instances Yes Global No
Table_open_cache_misses Yes Both No
Table_open_cache_overflows Yes Both No
tc-heuristic-recover Yes Yes
Tc_log_max_pages_used Yes Global No
Tc_log_page_size Yes Global No
Tc_log_page_waits Yes Global No
temp-pool Yes Yes
thread_cache_size Yes Yes Yes Global Yes
thread_concurrency Yes Yes Yes Global No
thread_handling Yes Yes Yes Global No
thread_pool_algorithm Yes Yes Yes Global No
thread_pool_high_priority_connection Yes Yes Yes Both Yes
thread_pool_max_unused_threads Yes Yes Yes Global Yes
thread_pool_prio_kickup_timer Yes Yes Yes Both Yes
thread_pool_size Yes Yes Yes Global No
thread_pool_stall_limit Yes Yes Yes Global Yes
thread_stack Yes Yes Yes Global No
Threads_cached Yes Global No
Threads_connected Yes Global No
Threads_created Yes Global No
Threads_running Yes Global No
time_format Yes Global No
time_zone Yes Both Yes
timed_mutexes Yes Yes Yes Global Yes
timestamp Yes Session Yes
tmp_table_size Yes Yes Yes Both Yes
tmpdir Yes Yes Yes Global No
transaction_alloc_block_size Yes Yes Yes Both Yes
transaction_allow_batching Yes Session Yes
transaction-isolation Yes Yes
- Variable: tx_isolation
transaction_prealloc_size Yes Yes Yes Both Yes
transaction-read-only Yes Yes
- Variable: tx_read_only
tx_isolation Yes Both Yes
tx_read_only Yes Both Yes
unique_checks Yes Both Yes
updatable_views_with_limit Yes Yes Yes Both Yes
Uptime Yes Global No
Uptime_since_flush_status Yes Global No
user Yes Yes
validate-password Yes Yes
validate_password_dictionary_file Yes Global Varies
validate_password_dictionary_file_last_parsed Yes Global No
validate_password_dictionary_file_words_count Yes Global No
validate_password_length Yes Global Yes
validate_password_mixed_case_count Yes Global Yes
validate_password_number_count Yes Global Yes
validate_password_policy Yes Global Yes
validate_password_special_char_count Yes Global Yes
validate_user_plugins Yes Global No
verbose Yes Yes
version Yes Global No
version_comment Yes Global No
version_compile_machine Yes Global No
version_compile_os Yes Global No
wait_timeout Yes Yes Yes Both Yes
warning_count Yes Session No

Notes:

1. This option is dynamic, but only the server should set this information. You should not set the value of this variable manually.

5.1.4 Server System Variable Reference

The following table lists all system variables applicable within mysqld.

The table lists command-line options (Cmd-line), options valid in configuration files (Option file), server system variables (System Var), and status variables (Status var) in one unified list, with an indication of where each option or variable is valid. If a server option set on the command line or in an option file differs from the name of the corresponding system variable, the variable name is noted immediately below the corresponding option. The scope of the variable (Var Scope) is Global, Session, or both. Please see the corresponding item descriptions for details on setting and using the variables. Where appropriate, direct links to further information about the items are provided.

Table 5.3 System Variable Summary

Name Cmd-Line Option File System Var Var Scope Dynamic
audit_log_buffer_size Yes Yes Yes Global No
audit_log_connection_policy Yes Yes Yes Global Yes
audit_log_current_session Yes Both No
audit_log_exclude_accounts Yes Yes Yes Global Yes
audit_log_file Yes Yes Yes Global No
audit_log_flush Yes Global Yes
audit_log_format Yes Yes Yes Global No
audit_log_include_accounts Yes Yes Yes Global Yes
audit_log_policy Yes Yes Yes Global Varies
audit_log_rotate_on_size Yes Yes Yes Global Yes
audit_log_statement_policy Yes Yes Yes Global Yes
audit_log_strategy Yes Yes Yes Global No
authentication_windows_log_level Yes Yes Yes Global No
authentication_windows_use_principal_name Yes Yes Yes Global No
auto_increment_increment Yes Both Yes
auto_increment_offset Yes Both Yes
autocommit Yes Yes Yes Both Yes
automatic_sp_privileges Yes Global Yes
avoid_temporal_upgrade Yes Yes Yes Global Yes
back_log Yes Global No
basedir Yes Yes Yes Global No
big-tables Yes Yes Yes
- Variable: big_tables Yes Both Yes
bind-address Yes Yes No
- Variable: bind_address Yes Global No
binlog_cache_size Yes Yes Yes Global Yes
binlog_checksum Yes Global Yes
binlog_direct_non_transactional_updates Yes Yes Yes Both Yes
binlog_error_action Yes Yes Yes Global Yes
binlog-format Yes Yes Yes
- Variable: binlog_format Yes Both Yes
binlog_gtid_simple_recovery Yes Yes Yes Global No
binlog_max_flush_queue_time Yes Global Yes
binlog_order_commits Yes Global Yes
binlog_row_image Yes Yes Yes Both Yes
binlog_rows_query_log_events Yes Yes Yes Both Yes
binlog_stmt_cache_size Yes Yes Yes Global Yes
binlogging_impossible_mode Yes Yes Yes Both Yes
block_encryption_mode Yes Yes Yes Both Yes
bulk_insert_buffer_size Yes Yes Yes Both Yes
character_set_client Yes Both Yes
character_set_connection Yes Both Yes
character_set_database (note 1) Yes Both Yes
character-set-filesystem Yes Yes Yes
- Variable: character_set_filesystem Yes Both Yes
character_set_results Yes Both Yes
character-set-server Yes Yes Yes
- Variable: character_set_server Yes Both Yes
character_set_system Yes Global No
character-sets-dir Yes Yes No
- Variable: character_sets_dir Yes Global No
collation_connection Yes Both Yes
collation_database (note 1) Yes Both Yes
collation-server Yes Yes Yes
- Variable: collation_server Yes Both Yes
completion_type Yes Yes Yes Both Yes
concurrent_insert Yes Yes Yes Global Yes
connect_timeout Yes Yes Yes Global Yes
connection_control_failed_connections_threshold Yes Yes Yes Global Yes
connection_control_max_connection_delay Yes Yes Yes Global Yes
connection_control_min_connection_delay Yes Yes Yes Global Yes
core_file Yes Global No
create_old_temporals Yes Yes Yes Global No
daemon_memcached_enable_binlog Yes Yes Yes Global No
daemon_memcached_engine_lib_name Yes Yes Yes Global No
daemon_memcached_engine_lib_path Yes Yes Yes Global No
daemon_memcached_option Yes Yes Yes Global No
daemon_memcached_r_batch_size Yes Yes Yes Global No
daemon_memcached_w_batch_size Yes Yes Yes Global No
datadir Yes Yes Yes Global No
date_format Yes Global No
datetime_format Yes Global No
debug Yes Yes Yes Both Yes
debug_sync Yes Session Yes
default-storage-engine Yes Yes Yes
- Variable: default_storage_engine Yes Both Yes
default_tmp_storage_engine Yes Yes Yes Both Yes
default_week_format Yes Yes Yes Both Yes
delay-key-write Yes Yes Yes
- Variable: delay_key_write Yes Global Yes
delayed_insert_limit Yes Yes Yes Global Yes
delayed_insert_timeout Yes Yes Yes Global Yes
delayed_queue_size Yes Yes Yes Global Yes
disable-gtid-unsafe-statements Yes Yes Yes Global No
disable_gtid_unsafe_statements Yes Yes Yes Global No
disconnect_on_expired_password Yes Yes Yes Global No
div_precision_increment Yes Yes Yes Both Yes
end_markers_in_json Yes Both Yes
enforce-gtid-consistency Yes Yes Yes Global No
enforce_gtid_consistency Yes Yes Yes Global No
engine-condition-pushdown Yes Yes Yes
- Variable: engine_condition_pushdown Yes Both Yes
eq_range_index_dive_limit Yes Both Yes
error_count Yes Session No
event-scheduler Yes Yes Yes
- Variable: event_scheduler Yes Global Yes
expire_logs_days Yes Yes Yes Global Yes
explicit_defaults_for_timestamp Yes Yes Yes Both Yes
external_user Yes Session No
flush Yes Yes Yes Global Yes
flush_time Yes Yes Yes Global Yes
foreign_key_checks Yes Both Yes
ft_boolean_syntax Yes Yes Yes Global Yes
ft_max_word_len Yes Yes Yes Global No
ft_min_word_len Yes Yes Yes Global No
ft_query_expansion_limit Yes Yes Yes Global No
ft_stopword_file Yes Yes Yes Global No
general-log Yes Yes Yes
- Variable: general_log Yes Global Yes
general_log_file Yes Yes Yes Global Yes
group_concat_max_len Yes Yes Yes Both Yes
gtid_done Yes Both No
gtid_executed Yes Both No
gtid_lost Yes Global No
gtid-mode Yes Yes No
- Variable: gtid_mode Yes Global No
gtid_mode Yes Global No
gtid_next Yes Session Yes
gtid_owned Yes Both No
gtid_purged Yes Global Yes
have_compress Yes Global No
have_crypt Yes Global No
have_csv Yes Global No
have_dynamic_loading Yes Global No
have_geometry Yes Global No
have_innodb Yes Global No
have_ndbcluster Yes Global No
have_openssl Yes Global No
have_partitioning Yes Global No
have_profiling Yes Global No
have_query_cache Yes Global No
have_rtree_keys Yes Global No
have_ssl Yes Global No
have_symlink Yes Global No
host_cache_size Yes Global Yes
hostname Yes Global No
identity Yes Session Yes
ignore-builtin-innodb Yes Yes No
- Variable: ignore_builtin_innodb Yes Global No
ignore_db_dirs Yes Global No
init_connect Yes Yes Yes Global Yes
init-file Yes Yes No
- Variable: init_file Yes Global No
init_slave Yes Yes Yes Global Yes
innodb_adaptive_flushing Yes Yes Yes Global Yes
innodb_adaptive_flushing_lwm Yes Yes Yes Global Yes
innodb_adaptive_hash_index Yes Yes Yes Global Yes
innodb_adaptive_max_sleep_delay Yes Yes Yes Global Yes
innodb_additional_mem_pool_size Yes Yes Yes Global No
innodb_api_bk_commit_interval Yes Yes Yes Global Yes
innodb_api_disable_rowlock Yes Yes Yes Global No
innodb_api_enable_binlog Yes Yes Yes Global No
innodb_api_enable_mdl Yes Yes Yes Global No
innodb_api_trx_level Yes Yes Yes Global Yes
innodb_autoextend_increment Yes Yes Yes Global Yes
innodb_autoinc_lock_mode Yes Yes Yes Global No
innodb_buffer_pool_dump_at_shutdown Yes Yes Yes Global Yes
innodb_buffer_pool_dump_now Yes Yes Yes Global Yes
innodb_buffer_pool_filename Yes Yes Yes Global Yes
innodb_buffer_pool_instances Yes Yes Yes Global No
innodb_buffer_pool_load_abort Yes Yes Yes Global Yes
innodb_buffer_pool_load_at_startup Yes Yes Yes Global No
innodb_buffer_pool_load_now Yes Yes Yes Global Yes
innodb_buffer_pool_size Yes Yes Yes Global No
innodb_change_buffer_max_size Yes Yes Yes Global Yes
innodb_change_buffering Yes Yes Yes Global Yes
innodb_change_buffering_debug Yes Yes Yes Global Yes
innodb_checksum_algorithm Yes Yes Yes Global Yes
innodb_checksums Yes Yes Yes Global No
innodb_cmp_per_index_enabled Yes Yes Yes Global Yes
innodb_commit_concurrency Yes Yes Yes Global Yes
innodb_compression_failure_threshold_pct Yes Yes Yes Global Yes
innodb_compression_level Yes Yes Yes Global Yes
innodb_compression_pad_pct_max Yes Yes Yes Global Yes
innodb_concurrency_tickets Yes Yes Yes Global Yes
innodb_data_file_path Yes Yes Yes Global No
innodb_data_home_dir Yes Yes Yes Global No
innodb_disable_sort_file_cache Yes Yes Yes Global Yes
innodb_doublewrite Yes Yes Yes Global No
innodb_fast_shutdown Yes Yes Yes Global Yes
innodb_fil_make_page_dirty_debug Yes Yes Yes Global Yes
innodb_file_format Yes Yes Yes Global Yes
innodb_file_format_check Yes Yes Yes Global No
innodb_file_format_max Yes Yes Yes Global Yes
innodb_file_per_table Yes Yes Yes Global Yes
innodb_flush_log_at_timeout Yes Global Yes
innodb_flush_log_at_trx_commit Yes Yes Yes Global Yes
innodb_flush_method Yes Yes Yes Global No
innodb_flush_neighbors Yes Yes Yes Global Yes
innodb_flushing_avg_loops Yes Yes Yes Global Yes
innodb_force_load_corrupted Yes Yes Yes Global No
innodb_force_recovery Yes Yes Yes Global No
innodb_ft_aux_table Yes Global Yes
innodb_ft_cache_size Yes Yes Yes Global No
innodb_ft_enable_diag_print Yes Yes Yes Global Yes
innodb_ft_enable_stopword Yes Yes Yes Both Yes
innodb_ft_max_token_size Yes Yes Yes Global No
innodb_ft_min_token_size Yes Yes Yes Global No
innodb_ft_num_word_optimize Yes Yes Yes Global Yes
innodb_ft_result_cache_limit Yes Yes Yes Global Yes
innodb_ft_server_stopword_table Yes Yes Yes Global Yes
innodb_ft_sort_pll_degree Yes Yes Yes Global No
innodb_ft_total_cache_size Yes Yes Yes Global No
innodb_ft_user_stopword_table Yes Yes Yes Both Yes
innodb_io_capacity Yes Yes Yes Global Yes
innodb_io_capacity_max Yes Yes Yes Global Yes
innodb_large_prefix Yes Yes Yes Global Yes
innodb_limit_optimistic_insert_debug Yes Yes Yes Global Yes
innodb_lock_wait_timeout Yes Yes Yes Both Yes
innodb_locks_unsafe_for_binlog Yes Yes Yes Global No
innodb_log_buffer_size Yes Yes Yes Global No
innodb_log_checkpoint_now Yes Yes Yes Global Yes
innodb_log_compressed_pages Yes Yes Yes Global Yes
innodb_log_file_size Yes Yes Yes Global No
innodb_log_files_in_group Yes Yes Yes Global No
innodb_log_group_home_dir Yes Yes Yes Global No
innodb_lru_scan_depth Yes Yes Yes Global Yes
innodb_max_dirty_pages_pct Yes Yes Yes Global Yes
innodb_max_dirty_pages_pct_lwm Yes Yes Yes Global Yes
innodb_max_purge_lag Yes Yes Yes Global Yes
innodb_max_purge_lag_delay Yes Yes Yes Global Yes
innodb_mirrored_log_groups Yes Yes Yes Global No
innodb_monitor_disable Yes Yes Yes Global Yes
innodb_monitor_enable Yes Yes Yes Global Yes
innodb_monitor_reset Yes Yes Yes Global Yes
innodb_monitor_reset_all Yes Yes Yes Global Yes
innodb_numa_interleave Yes Yes Yes Global No
innodb_old_blocks_pct Yes Yes Yes Global Yes
innodb_old_blocks_time Yes Yes Yes Global Yes
innodb_online_alter_log_max_size Yes Yes Yes Global Yes
innodb_open_files Yes Yes Yes Global No
innodb_optimize_fulltext_only Yes Yes Yes Global Yes
innodb_page_size Yes Yes Yes Global No
innodb_print_all_deadlocks Yes Yes Yes Global Yes
innodb_purge_batch_size Yes Yes Yes Global Yes
innodb_purge_threads Yes Yes Yes Global No
innodb_random_read_ahead Yes Yes Yes Global Yes
innodb_read_ahead_threshold Yes Yes Yes Global Yes
innodb_read_io_threads Yes Yes Yes Global No
innodb_read_only Yes Yes Yes Global No
innodb_replication_delay Yes Yes Yes Global Yes
innodb_rollback_on_timeout Yes Yes Yes Global No
innodb_rollback_segments Yes Yes Yes Global Yes
innodb_saved_page_number_debug Yes Yes Yes Global Yes
innodb_sort_buffer_size Yes Yes Yes Global No
innodb_spin_wait_delay Yes Yes Yes Global Yes
innodb_stats_auto_recalc Yes Yes Yes Global Yes
innodb_stats_include_delete_marked Yes Yes Yes Global Yes
innodb_stats_method Yes Yes Yes Global Yes
innodb_stats_on_metadata Yes Yes Yes Global Yes
innodb_stats_persistent Yes Yes Yes Global Yes
innodb_stats_persistent_sample_pages Yes Yes Yes Global Yes
innodb_stats_sample_pages Yes Yes Yes Global Yes
innodb_stats_transient_sample_pages Yes Yes Yes Global Yes
innodb_status_output Yes Yes Yes Global Yes
innodb_status_output_locks Yes Yes Yes Global Yes
innodb_strict_mode Yes Yes Yes Both Yes
innodb_support_xa Yes Yes Yes Both Yes
innodb_sync_array_size Yes Yes Yes Global No
innodb_sync_spin_loops Yes Yes Yes Global Yes
innodb_table_locks Yes Yes Yes Both Yes
innodb_thread_concurrency Yes Yes Yes Global Yes
innodb_thread_sleep_delay Yes Yes Yes Global Yes
innodb_tmpdir Yes Yes Yes Both Yes
innodb_trx_purge_view_update_only_debug Yes Yes Yes Global Yes
innodb_trx_rseg_n_slots_debug Yes Yes Yes Global Yes
innodb_undo_directory Yes Yes Yes Global No
innodb_undo_logs Yes Yes Yes Global Yes
innodb_undo_tablespaces Yes Yes Yes Global No
innodb_use_native_aio Yes Yes Yes Global No
innodb_use_sys_malloc Yes Yes Yes Global No
innodb_version Yes Global No
innodb_write_io_threads Yes Yes Yes Global No
insert_id Yes Session Yes
interactive_timeout Yes Yes Yes Both Yes
join_buffer_size Yes Yes Yes Both Yes
keep_files_on_create Yes Yes Yes Both Yes
key_buffer_size Yes Yes Yes Global Yes
key_cache_age_threshold Yes Yes Yes Global Yes
key_cache_block_size Yes Yes Yes Global Yes
key_cache_division_limit Yes Yes Yes Global Yes
language Yes Yes Yes Global No
large_files_support Yes Global No
large_page_size Yes Global No
large-pages Yes Yes No
- Variable: large_pages Yes Global No
last_insert_id Yes Session Yes
lc-messages Yes Yes Yes
- Variable: lc_messages Yes Both Yes
lc-messages-dir Yes Yes No
- Variable: lc_messages_dir Yes Global No
lc_time_names Yes Both Yes
license Yes Global No
local_infile Yes Global Yes
lock_wait_timeout Yes Yes Yes Both Yes
locked_in_memory Yes Global No
log Yes Yes Yes Global Yes
log-bin Yes Yes Yes Global No
log_bin Yes Global No
log_bin_basename Yes Global No
log_bin_index Yes Global No
log-bin-trust-function-creators Yes Yes Yes
- Variable: log_bin_trust_function_creators Yes Global Yes
log-bin-use-v1-row-events Yes Yes No
- Variable: log_bin_use_v1_row_events Yes Global No
log_bin_use_v1_row_events Yes Yes Yes Global No
log-error Yes Yes No
- Variable: log_error Yes Global No
log_output Yes Yes Yes Global Yes
log-queries-not-using-indexes Yes Yes Yes
- Variable: log_queries_not_using_indexes Yes Global Yes
log-slave-updates Yes Yes No
- Variable: log_slave_updates Yes Global No
log_slave_updates Yes Yes Yes Global No
log_slow_admin_statements Yes Global Yes
log-slow-queries Yes Yes Yes
- Variable: log_slow_queries Yes Global Yes
log_slow_slave_statements Yes Global Yes
log_throttle_queries_not_using_indexes Yes Global Yes
log-warnings Yes Yes Yes
- Variable: log_warnings Yes Varies Yes
long_query_time Yes Yes Yes Both Yes
low-priority-updates Yes Yes Yes
- Variable: low_priority_updates Yes Both Yes
lower_case_file_system Yes Global No
lower_case_table_names Yes Yes Yes Global No
master_info_repository Yes Yes Yes Global Yes
master_verify_checksum Yes Global Yes
max_allowed_packet Yes Yes Yes Both Yes
max_binlog_cache_size Yes Yes Yes Global Yes
max_binlog_size Yes Yes Yes Global Yes
max_binlog_stmt_cache_size Yes Yes Yes Global Yes
max_connect_errors Yes Yes Yes Global Yes
max_connections Yes Yes Yes Global Yes
max_delayed_threads Yes Yes Yes Both Yes
max_digest_length Yes Yes Yes Global No
max_error_count Yes Yes Yes Both Yes
max_heap_table_size Yes Yes Yes Both Yes
max_insert_delayed_threads Yes Both Yes
max_join_size Yes Yes Yes Both Yes
max_length_for_sort_data Yes Yes Yes Both Yes
max_prepared_stmt_count Yes Yes Yes Global Yes
max_relay_log_size Yes Yes Yes Global Yes
max_seeks_for_key Yes Yes Yes Both Yes
max_sort_length Yes Yes Yes Both Yes
max_sp_recursion_depth Yes Yes Yes Both Yes
max_tmp_tables Yes Both Yes
max_user_connections Yes Yes Yes Both Yes
max_write_lock_count Yes Yes Yes Global Yes
metadata_locks_cache_size Yes Global No
metadata_locks_hash_instances Yes Global No
min-examined-row-limit Yes Yes Yes Both Yes
multi_range_count Yes Yes Yes Both Yes
myisam_data_pointer_size Yes Yes Yes Global Yes
myisam_max_sort_file_size Yes Yes Yes Global Yes
myisam_mmap_size Yes Yes Yes Global No
myisam_recover_options Yes Global No
myisam_repair_threads Yes Yes Yes Both Yes
myisam_sort_buffer_size Yes Yes Yes Both Yes
myisam_stats_method Yes Yes Yes Both Yes
myisam_use_mmap Yes Yes Yes Global Yes
mysql_firewall_max_query_size Yes Yes Yes Global No
mysql_firewall_mode Yes Yes Yes Global Yes
mysql_firewall_trace Yes Yes Yes Global Yes
named_pipe Yes Global No
ndb_autoincrement_prefetch_sz Yes Yes Yes Both Yes
ndb-batch-size Yes Yes Yes Global No
ndb-blob-read-batch-bytes Yes Yes Yes Both Yes
ndb-blob-write-batch-bytes Yes Yes Yes Both Yes
ndb_cache_check_time Yes Yes Yes Global Yes
ndb_clear_apply_status Yes Yes Global Yes
ndb-cluster-connection-pool Yes Yes Yes Global No
Ndb_conflict_last_conflict_epoch Yes Global No
ndb-deferred-constraints Yes Yes Yes
- Variable: ndb_deferred_constraints Yes Both Yes
ndb_deferred_constraints Yes Yes Yes Both Yes
ndb-distribution Yes Yes Yes
- Variable: ndb_distribution Yes Global Yes
ndb_distribution Yes Yes Yes Global Yes
ndb_eventbuffer_free_percent Yes Yes Yes Global Yes
ndb_eventbuffer_max_alloc Yes Yes Yes Global Yes
ndb_extra_logging Yes Yes Yes Global Yes
ndb_force_send Yes Yes Yes Both Yes
ndb_index_stat_cache_entries Yes Yes Yes Both Yes
ndb_index_stat_enable Yes Yes Yes Both Yes
ndb_index_stat_option Yes Yes Yes Both Yes
ndb_index_stat_update_freq Yes Yes Yes Both Yes
ndb_join_pushdown Yes Both Yes
ndb-log-apply-status Yes Yes No
- Variable: ndb_log_apply_status Yes Global No
ndb_log_apply_status Yes Yes Yes Global No
ndb_log_bin Yes Yes Both Yes
ndb_log_binlog_index Yes Yes Global Yes
ndb-log-empty-epochs Yes Yes Yes Global Yes
ndb_log_empty_epochs Yes Yes Yes Global Yes
ndb-log-empty-update Yes Yes Yes Global Yes
ndb_log_empty_update Yes Yes Yes Global Yes
ndb-log-exclusive-reads Yes Yes Yes
- Variable: ndb_log_exclusive_reads Yes Both Yes
ndb_log_exclusive_reads Yes Yes Yes Both Yes
ndb-log-orig Yes Yes No
- Variable: ndb_log_orig Yes Global No
ndb_log_orig Yes Yes Yes Global No
ndb-log-transaction-id Yes Yes No
- Variable: ndb_log_transaction_id Yes Global No
ndb_log_transaction_id Yes Global No
ndb-log-update-as-write Yes Yes Yes Global Yes
ndb-log-update-minimal Yes Yes Yes Global Yes
ndb_log_updated_only Yes Yes Yes Global Yes
ndb_optimization_delay Yes Global Yes
ndb_optimized_node_selection Yes Yes Yes Global No
ndb_recv_thread_activation_threshold Yes Global Yes
ndb_recv_thread_cpu_mask Yes Global Yes
ndb_report_thresh_binlog_epoch_slip Yes Yes Yes Global Yes
ndb_report_thresh_binlog_mem_usage Yes Yes Yes Global Yes
ndb_show_foreign_key_mock_tables Yes Yes Yes Global Yes
ndb_slave_conflict_role Yes Yes Yes Global Yes
Ndb_slave_max_replicated_epoch Yes Global No
ndb_table_no_logging Yes Session Yes
ndb_table_temporary Yes Session Yes
ndb_use_copying_alter_table Yes Both No
ndb_use_exact_count Yes Both Yes
ndb_use_transactions Yes Yes Yes Both Yes
ndb_version Yes Global No
ndb_version_string Yes Global No
ndb-wait-connected Yes Yes Yes Global No
ndb-wait-setup Yes Yes Yes Global No
ndbinfo_database Yes Global No
ndbinfo_max_bytes Yes Yes Both Yes
ndbinfo_max_rows Yes Yes Both Yes
ndbinfo_offline Yes Global Yes
ndbinfo_show_hidden Yes Yes Both Yes
ndbinfo_table_prefix Yes Yes Both Yes
ndbinfo_version Yes Global No
net_buffer_length Yes Yes Yes Both Yes
net_read_timeout Yes Yes Yes Both Yes
net_retry_count Yes Yes Yes Both Yes
net_write_timeout Yes Yes Yes Both Yes
new Yes Yes Yes Both Yes
old Yes Yes Yes Global No
old-alter-table Yes Yes Yes
- Variable: old_alter_table Yes Both Yes
old_passwords Yes Both Yes
open-files-limit Yes Yes No
- Variable: open_files_limit Yes Global No
optimizer_join_cache_level Yes Yes Yes Both Yes
optimizer_prune_level Yes Yes Yes Both Yes
optimizer_search_depth Yes Yes Yes Both Yes
optimizer_switch Yes Yes Yes Both Yes
optimizer_trace Yes Both Yes
optimizer_trace_features Yes Both Yes
optimizer_trace_limit Yes Both Yes
optimizer_trace_max_mem_size Yes Both Yes
optimizer_trace_offset Yes Both Yes
performance_schema Yes Yes Yes Global No
performance_schema_accounts_size Yes Yes Yes Global No
performance_schema_digests_size Yes Yes Yes Global No
performance_schema_events_stages_history_long_size Yes Yes Yes Global No
performance_schema_events_stages_history_size Yes Yes Yes Global No
performance_schema_events_statements_history_long_size Yes Yes Yes Global No
performance_schema_events_statements_history_size Yes Yes Yes Global No
performance_schema_events_waits_history_long_size Yes Yes Yes Global No
performance_schema_events_waits_history_size Yes Yes Yes Global No
performance_schema_hosts_size Yes Yes Yes Global No
performance_schema_max_cond_classes Yes Yes Yes Global No
performance_schema_max_cond_instances Yes Yes Yes Global No
performance_schema_max_digest_length Yes Yes Yes Global No
performance_schema_max_file_classes Yes Yes Yes Global No
performance_schema_max_file_handles Yes Yes Yes Global No
performance_schema_max_file_instances Yes Yes Yes Global No
performance_schema_max_mutex_classes Yes Yes Yes Global No
performance_schema_max_mutex_instances Yes Yes Yes Global No
performance_schema_max_rwlock_classes Yes Yes Yes Global No
performance_schema_max_rwlock_instances Yes Yes Yes Global No
performance_schema_max_socket_classes Yes Yes Yes Global No
performance_schema_max_socket_instances Yes Yes Yes Global No
performance_schema_max_stage_classes Yes Yes Yes Global No
performance_schema_max_statement_classes Yes Yes Yes Global No
performance_schema_max_table_handles Yes Yes Yes Global No
performance_schema_max_table_instances Yes Yes Yes Global No
performance_schema_max_thread_classes Yes Yes Yes Global No
performance_schema_max_thread_instances Yes Yes Yes Global No
performance_schema_session_connect_attrs_size Yes Yes Yes Global No
performance_schema_setup_actors_size Yes Yes Yes Global No
performance_schema_setup_objects_size Yes Yes Yes Global No
performance_schema_users_size Yes Yes Yes Global No
pid-file Yes Yes No
- Variable: pid_file Yes Global No
plugin_dir Yes Yes Yes Global No
port Yes Yes Yes Global No
preload_buffer_size Yes Yes Yes Both Yes
profiling Yes Both Yes
profiling_history_size Yes Yes Yes Both Yes
protocol_version Yes Global No
proxy_user Yes Session No
pseudo_slave_mode Yes Session Yes
pseudo_thread_id Yes Session Yes
query_alloc_block_size Yes Yes Yes Both Yes
query_cache_limit Yes Yes Yes Global Yes
query_cache_min_res_unit Yes Yes Yes Global Yes
query_cache_size Yes Yes Yes Global Yes
query_cache_type Yes Yes Yes Both Yes
query_cache_wlock_invalidate Yes Yes Yes Both Yes
query_prealloc_size Yes Yes Yes Both Yes
rand_seed1 Yes Session Yes
rand_seed2 Yes Session Yes
range_alloc_block_size Yes Yes Yes Both Yes
read_buffer_size Yes Yes Yes Both Yes
read_only Yes Yes Yes Global Yes
read_rnd_buffer_size Yes Yes Yes Both Yes
relay-log Yes Yes No
- Variable: relay_log Yes Global No
relay_log_basename Yes Global No
relay-log-index Yes Yes No
- Variable: relay_log_index Yes Global No
relay_log_index Yes Yes Yes Global No
relay_log_info_file Yes Yes Yes Global No
relay_log_info_repository Yes Global Yes
relay_log_purge Yes Yes Yes Global Yes
relay_log_recovery Yes Yes Yes Global Varies
relay_log_space_limit Yes Yes Yes Global No
report-host Yes Yes No
- Variable: report_host Yes Global No
report-password Yes Yes No
- Variable: report_password Yes Global No
report-port Yes Yes No
- Variable: report_port Yes Global No
report-user Yes Yes No
- Variable: report_user Yes Global No
rpl_semi_sync_master_enabled Yes Global Yes
rpl_semi_sync_master_timeout Yes Global Yes
rpl_semi_sync_master_trace_level Yes Global Yes
rpl_semi_sync_master_wait_no_slave Yes Global Yes
rpl_semi_sync_slave_enabled Yes Global Yes
rpl_semi_sync_slave_trace_level Yes Global Yes
rpl_stop_slave_timeout Yes Yes Yes Global Yes
secure-auth Yes Yes Yes
- Variable: secure_auth Yes Global Yes
secure-file-priv Yes Yes No
- Variable: secure_file_priv Yes Global No
server-id Yes Yes Yes
- Variable: server_id Yes Global Yes
server-id-bits Yes Yes No
- Variable: server_id_bits Yes Global No
server_id_bits Yes Yes Yes Global No
server_uuid Yes Global No
sha256_password_private_key_path Yes Yes Yes Global No
sha256_password_public_key_path Yes Yes Yes Global No
shared_memory Yes Yes Yes Global No
shared_memory_base_name Yes Yes Yes Global No
show_old_temporals Yes Yes Yes Both Yes
simplified_binlog_gtid_recovery Yes Yes Yes Global No
skip_external_locking Yes Yes Yes Global No
skip-name-resolve Yes Yes No
- Variable: skip_name_resolve Yes Global No
skip-networking Yes Yes No
- Variable: skip_networking Yes Global No
skip-show-database Yes Yes No
- Variable: skip_show_database Yes Global No
slave_allow_batching Yes Yes Yes Global Yes
slave_checkpoint_group Yes Yes Yes Global Yes
slave_checkpoint_period Yes Yes Yes Global Yes
slave_compressed_protocol Yes Yes Yes Global Yes
slave_exec_mode Yes Yes Yes Global Yes
slave-load-tmpdir Yes Yes No
- Variable: slave_load_tmpdir Yes Global No
slave_max_allowed_packet Yes Global Yes
slave-net-timeout Yes Yes Yes
- Variable: slave_net_timeout Yes Global Yes
slave_parallel_workers Yes Yes Global Yes
slave_pending_jobs_size_max Yes Yes Global Yes
slave_rows_search_algorithms Yes Global Yes
slave-skip-errors Yes Yes No
- Variable: slave_skip_errors Yes Global No
slave_sql_verify_checksum Yes Global Yes
slave_transaction_retries Yes Yes Yes Global Yes
slave_type_conversions Yes Yes Yes Global No
slow_launch_time Yes Yes Yes Global Yes
slow-query-log Yes Yes Yes
- Variable: slow_query_log Yes Global Yes
slow_query_log_file Yes Yes Yes Global Yes
socket Yes Yes Yes Global No
sort_buffer_size Yes Yes Yes Both Yes
sql_auto_is_null Yes Both Yes
sql_big_selects Yes Both Yes
sql_big_tables Yes Both Yes
sql_buffer_result Yes Both Yes
sql_log_bin Yes Session Yes
sql_log_off Yes Both Yes
sql_low_priority_updates Yes Both Yes
sql_max_join_size Yes Both Yes
sql-mode Yes Yes Yes
- Variable: sql_mode Yes Both Yes
sql_notes Yes Both Yes
sql_quote_show_create Yes Both Yes
sql_safe_updates Yes Both Yes
sql_select_limit Yes Both Yes
sql_slave_skip_counter Yes Global Yes
sql_warnings Yes Both Yes
ssl-ca Yes Yes No
- Variable: ssl_ca Yes Global No
ssl-capath Yes Yes No
- Variable: ssl_capath Yes Global No
ssl-cert Yes Yes No
- Variable: ssl_cert Yes Global No
ssl-cipher Yes Yes No
- Variable: ssl_cipher Yes Global No
ssl-crl Yes Yes No
- Variable: ssl_crl Yes Global No
ssl-crlpath Yes Yes No
- Variable: ssl_crlpath Yes Global No
ssl-key Yes Yes No
- Variable: ssl_key Yes Global No
storage_engine Yes Both Yes
stored_program_cache Yes Yes Yes Global Yes
sync_binlog Yes Yes Yes Global Yes
sync_frm Yes Yes Yes Global Yes
sync_master_info Yes Yes Yes Global Yes
sync_relay_log Yes Yes Yes Global Yes
sync_relay_log_info Yes Yes Yes Global Yes
system_time_zone Yes Global No
table_definition_cache Yes Global Yes
table_open_cache Yes Global Yes
table_open_cache_instances Yes Global No
thread_cache_size Yes Yes Yes Global Yes
thread_concurrency Yes Yes Yes Global No
thread_handling Yes Yes Yes Global No
thread_pool_algorithm Yes Yes Yes Global No
thread_pool_high_priority_connection Yes Yes Yes Both Yes
thread_pool_max_unused_threads Yes Yes Yes Global Yes
thread_pool_prio_kickup_timer Yes Yes Yes Both Yes
thread_pool_size Yes Yes Yes Global No
thread_pool_stall_limit Yes Yes Yes Global Yes
thread_stack Yes Yes Yes Global No
time_format Yes Global No
time_zone Yes Both Yes
timed_mutexes Yes Yes Yes Global Yes
timestamp Yes Session Yes
tmp_table_size Yes Yes Yes Both Yes
tmpdir Yes Yes Yes Global No
transaction_alloc_block_size Yes Yes Yes Both Yes
transaction_allow_batching Yes Session Yes
transaction_prealloc_size Yes Yes Yes Both Yes
tx_isolation Yes Both Yes
tx_read_only Yes Both Yes
unique_checks Yes Both Yes
updatable_views_with_limit Yes Yes Yes Both Yes
validate_password_dictionary_file Yes Global Varies
validate_password_length Yes Global Yes
validate_password_mixed_case_count Yes Global Yes
validate_password_number_count Yes Global Yes
validate_password_policy Yes Global Yes
validate_password_special_char_count Yes Global Yes
validate_user_plugins Yes Global No
version Yes Global No
version_comment Yes Global No
version_compile_machine Yes Global No
version_compile_os Yes Global No
wait_timeout Yes Yes Yes Both Yes
warning_count Yes Session No

Notes:

1. This option is dynamic, but only the server should set this information. You should not set the value of this variable manually.

5.1.5 Server Status Variable Reference

The following table lists all status variables applicable within mysqld.

The table lists each variable's data type and scope. The last column indicates whether the scope for each variable is Global, Session, or both. Please see the corresponding item descriptions for details on setting and using the variables. Where appropriate, direct links to further information about the items are provided.

Table 5.4 Status Variable Summary

Variable Name Variable Type Variable Scope
Aborted_clients Integer Global
Aborted_connects Integer Global
Audit_log_current_size Integer Global
Audit_log_event_max_drop_size Integer Global
Audit_log_events Integer Global
Audit_log_events_filtered Integer Global
Audit_log_events_lost Integer Global
Audit_log_events_written Integer Global
Audit_log_total_size Integer Global
Audit_log_write_waits Integer Global
Binlog_cache_disk_use Integer Global
Binlog_cache_use Integer Global
Binlog_stmt_cache_disk_use Integer Global
Binlog_stmt_cache_use Integer Global
Bytes_received Integer Both
Bytes_sent Integer Both
Com_admin_commands Integer Both
Com_alter_db Integer Both
Com_alter_db_upgrade Integer Both
Com_alter_event Integer Both
Com_alter_function Integer Both
Com_alter_procedure Integer Both
Com_alter_server Integer Both
Com_alter_table Integer Both
Com_alter_tablespace Integer Both
Com_alter_user Integer Both
Com_analyze Integer Both
Com_assign_to_keycache Integer Both
Com_begin Integer Both
Com_binlog Integer Both
Com_call_procedure Integer Both
Com_change_db Integer Both
Com_change_master Integer Both
Com_check Integer Both
Com_checksum Integer Both
Com_commit Integer Both
Com_create_db Integer Both
Com_create_event Integer Both
Com_create_function Integer Both
Com_create_index Integer Both
Com_create_procedure Integer Both
Com_create_server Integer Both
Com_create_table Integer Both
Com_create_trigger Integer Both
Com_create_udf Integer Both
Com_create_user Integer Both
Com_create_view Integer Both
Com_dealloc_sql Integer Both
Com_delete Integer Both
Com_delete_multi Integer Both
Com_do Integer Both
Com_drop_db Integer Both
Com_drop_event Integer Both
Com_drop_function Integer Both
Com_drop_index Integer Both
Com_drop_procedure Integer Both
Com_drop_server Integer Both
Com_drop_table Integer Both
Com_drop_trigger Integer Both
Com_drop_user Integer Both
Com_drop_view Integer Both
Com_empty_query Integer Both
Com_execute_sql Integer Both
Com_flush Integer Both
Com_get_diagnostics Integer Both
Com_grant Integer Both
Com_ha_close Integer Both
Com_ha_open Integer Both
Com_ha_read Integer Both
Com_help Integer Both
Com_insert Integer Both
Com_insert_select Integer Both
Com_install_plugin Integer Both
Com_kill Integer Both
Com_load Integer Both
Com_lock_tables Integer Both
Com_optimize Integer Both
Com_preload_keys Integer Both
Com_prepare_sql Integer Both
Com_purge Integer Both
Com_purge_before_date Integer Both
Com_release_savepoint Integer Both
Com_rename_table Integer Both
Com_rename_user Integer Both
Com_repair Integer Both
Com_replace Integer Both
Com_replace_select Integer Both
Com_reset Integer Both
Com_resignal Integer Both
Com_revoke Integer Both
Com_revoke_all Integer Both
Com_rollback Integer Both
Com_rollback_to_savepoint Integer Both
Com_savepoint Integer Both
Com_select Integer Both
Com_set_option Integer Both
Com_show_authors Integer Both
Com_show_binlog_events Integer Both
Com_show_binlogs Integer Both
Com_show_charsets Integer Both
Com_show_collations Integer Both
Com_show_contributors Integer Both
Com_show_create_db Integer Both
Com_show_create_event Integer Both
Com_show_create_func Integer Both
Com_show_create_proc Integer Both
Com_show_create_table Integer Both
Com_show_create_trigger Integer Both
Com_show_databases Integer Both
Com_show_engine_logs Integer Both
Com_show_engine_mutex Integer Both
Com_show_engine_status Integer Both
Com_show_errors Integer Both
Com_show_events Integer Both
Com_show_fields Integer Both
Com_show_function_code Integer Both
Com_show_function_status Integer Both
Com_show_grants Integer Both
Com_show_keys Integer Both
Com_show_master_status Integer Both
Com_show_ndb_status Integer Both
Com_show_new_master Integer Both
Com_show_open_tables Integer Both
Com_show_plugins Integer Both
Com_show_privileges Integer Both
Com_show_procedure_code Integer Both
Com_show_procedure_status Integer Both
Com_show_processlist Integer Both
Com_show_profile Integer Both
Com_show_profiles Integer Both
Com_show_relaylog_events Integer Both
Com_show_slave_hosts Integer Both
Com_show_slave_status Integer Both
Com_show_status Integer Both
Com_show_storage_engines Integer Both
Com_show_table_status Integer Both
Com_show_tables Integer Both
Com_show_triggers Integer Both
Com_show_variables Integer Both
Com_show_warnings Integer Both
Com_signal Integer Both
Com_slave_start Integer Both
Com_slave_stop Integer Both
Com_stmt_close Integer Both
Com_stmt_execute Integer Both
Com_stmt_fetch Integer Both
Com_stmt_prepare Integer Both
Com_stmt_reprepare Integer Both
Com_stmt_reset Integer Both
Com_stmt_send_long_data Integer Both
Com_truncate Integer Both
Com_uninstall_plugin Integer Both
Com_unlock_tables Integer Both
Com_update Integer Both
Com_update_multi Integer Both
Com_xa_commit Integer Both
Com_xa_end Integer Both
Com_xa_prepare Integer Both
Com_xa_recover Integer Both
Com_xa_rollback Integer Both
Com_xa_start Integer Both
Compression Integer Session
Connection_control_delay_generated Integer Global
Connection_errors_accept Integer Global
Connection_errors_internal Integer Global
Connection_errors_max_connections Integer Global
Connection_errors_peer_address Integer Global
Connection_errors_select Integer Global
Connection_errors_tcpwrap Integer Global
Connections Integer Global
Created_tmp_disk_tables Integer Both
Created_tmp_files Integer Global
Created_tmp_tables Integer Both
Delayed_errors Integer Global
Delayed_insert_threads Integer Global
Delayed_writes Integer Global
Firewall_access_denied Integer Global
Firewall_access_granted Integer Global
Firewall_cached_entries Integer Global
Flush_commands Integer Global
Handler_commit Integer Both
Handler_delete Integer Both
Handler_discover Integer Both
Handler_external_lock Integer Both
Handler_mrr_init Integer Both
Handler_prepare Integer Both
Handler_read_first Integer Both
Handler_read_key Integer Both
Handler_read_last Integer Both
Handler_read_next Integer Both
Handler_read_prev Integer Both
Handler_read_rnd Integer Both
Handler_read_rnd_next Integer Both
Handler_rollback Integer Both
Handler_savepoint Integer Both
Handler_savepoint_rollback Integer Both
Handler_update Integer Both
Handler_write Integer Both
Innodb_available_undo_logs Integer Global
Innodb_buffer_pool_bytes_data Integer Global
Innodb_buffer_pool_bytes_dirty Integer Global
Innodb_buffer_pool_dump_status String Global
Innodb_buffer_pool_load_status String Global
Innodb_buffer_pool_pages_data Integer Global
Innodb_buffer_pool_pages_dirty Integer Global
Innodb_buffer_pool_pages_flushed Integer Global
Innodb_buffer_pool_pages_free Integer Global
Innodb_buffer_pool_pages_latched Integer Global
Innodb_buffer_pool_pages_misc Integer Global
Innodb_buffer_pool_pages_total Integer Global
Innodb_buffer_pool_read_ahead Integer Global
Innodb_buffer_pool_read_ahead_evicted Integer Global
Innodb_buffer_pool_read_ahead_rnd Integer Global
Innodb_buffer_pool_read_requests Integer Global
Innodb_buffer_pool_reads Integer Global
Innodb_buffer_pool_wait_free Integer Global
Innodb_buffer_pool_write_requests Integer Global
Innodb_data_fsyncs Integer Global
Innodb_data_pending_fsyncs Integer Global
Innodb_data_pending_reads Integer Global
Innodb_data_pending_writes Integer Global
Innodb_data_read Integer Global
Innodb_data_reads Integer Global
Innodb_data_writes Integer Global
Innodb_data_written Integer Global
Innodb_dblwr_pages_written Integer Global
Innodb_dblwr_writes Integer Global
Innodb_have_atomic_builtins Integer Global
Innodb_log_waits Integer Global
Innodb_log_write_requests Integer Global
Innodb_log_writes Integer Global
Innodb_num_open_files Integer Global
Innodb_os_log_fsyncs Integer Global
Innodb_os_log_pending_fsyncs Integer Global
Innodb_os_log_pending_writes Integer Global
Innodb_os_log_written Integer Global
Innodb_page_size Integer Global
Innodb_pages_created Integer Global
Innodb_pages_read Integer Global
Innodb_pages_written Integer Global
Innodb_row_lock_current_waits Integer Global
Innodb_row_lock_time Integer Global
Innodb_row_lock_time_avg Integer Global
Innodb_row_lock_time_max Integer Global
Innodb_row_lock_waits Integer Global
Innodb_rows_deleted Integer Global
Innodb_rows_inserted Integer Global
Innodb_rows_read Integer Global
Innodb_rows_updated Integer Global
Innodb_truncated_status_writes Integer Global
Key_blocks_not_flushed Integer Global
Key_blocks_unused Integer Global
Key_blocks_used Integer Global
Key_read_requests Integer Global
Key_reads Integer Global
Key_write_requests Integer Global
Key_writes Integer Global
Last_query_cost Numeric Session
Last_query_partial_plans Integer Session
Max_used_connections Integer Global
Ndb_api_bytes_received_count Integer Global
Ndb_api_bytes_received_count_session Integer Session
Ndb_api_bytes_received_count_slave Integer Global
Ndb_api_bytes_sent_count Integer Global
Ndb_api_bytes_sent_count_session Integer Session
Ndb_api_bytes_sent_count_slave Integer Global
Ndb_api_event_bytes_count Integer Global
Ndb_api_event_bytes_count_injector Integer Global
Ndb_api_event_data_count Integer Global
Ndb_api_event_data_count_injector Integer Global
Ndb_api_event_nondata_count Integer Global
Ndb_api_event_nondata_count_injector Integer Global
Ndb_api_pk_op_count Integer Global
Ndb_api_pk_op_count_session Integer Session
Ndb_api_pk_op_count_slave Integer Global
Ndb_api_pruned_scan_count Integer Global
Ndb_api_pruned_scan_count_session Integer Session
Ndb_api_pruned_scan_count_slave Integer Global
Ndb_api_range_scan_count Integer Global
Ndb_api_range_scan_count_session Integer Session
Ndb_api_range_scan_count_slave Integer Global
Ndb_api_read_row_count Integer Global
Ndb_api_read_row_count_session Integer Session
Ndb_api_read_row_count_slave Integer Global
Ndb_api_scan_batch_count Integer Global
Ndb_api_scan_batch_count_session Integer Session
Ndb_api_scan_batch_count_slave Integer Global
Ndb_api_table_scan_count Integer Global
Ndb_api_table_scan_count_session Integer Session
Ndb_api_table_scan_count_slave Integer Global
Ndb_api_trans_abort_count Integer Global
Ndb_api_trans_abort_count_session Integer Session
Ndb_api_trans_abort_count_slave Integer Global
Ndb_api_trans_close_count Integer Global
Ndb_api_trans_close_count_session Integer Session
Ndb_api_trans_close_count_slave Integer Global
Ndb_api_trans_commit_count Integer Global
Ndb_api_trans_commit_count_session Integer Session
Ndb_api_trans_commit_count_slave Integer Global
Ndb_api_trans_local_read_row_count Integer Global
Ndb_api_trans_local_read_row_count_session Integer Session
Ndb_api_trans_local_read_row_count_slave Integer Global
Ndb_api_trans_start_count Integer Global
Ndb_api_trans_start_count_session Integer Session
Ndb_api_trans_start_count_slave Integer Global
Ndb_api_uk_op_count Integer Global
Ndb_api_uk_op_count_session Integer Session
Ndb_api_uk_op_count_slave Integer Global
Ndb_api_wait_exec_complete_count Integer Global
Ndb_api_wait_exec_complete_count_session Integer Session
Ndb_api_wait_exec_complete_count_slave Integer Global
Ndb_api_wait_meta_request_count Integer Global
Ndb_api_wait_meta_request_count_session Integer Session
Ndb_api_wait_meta_request_count_slave Integer Global
Ndb_api_wait_nanos_count Integer Global
Ndb_api_wait_nanos_count_session Integer Session
Ndb_api_wait_nanos_count_slave Integer Global
Ndb_api_wait_scan_result_count Integer Global
Ndb_api_wait_scan_result_count_session Integer Session
Ndb_api_wait_scan_result_count_slave Integer Global
Ndb_cluster_node_id Integer Both
Ndb_config_from_host Integer Both
Ndb_config_from_port Integer Both
Ndb_conflict_fn_epoch Integer Global
Ndb_conflict_fn_epoch_trans Integer Global
Ndb_conflict_fn_epoch2 Integer Global
Ndb_conflict_fn_epoch2_trans Integer Global
Ndb_conflict_fn_max Integer Global
Ndb_conflict_fn_max_del_win Integer Global
Ndb_conflict_fn_old Integer Global
Ndb_conflict_last_stable_epoch Integer Global
Ndb_conflict_reflected_op_discard_count Integer Global
Ndb_conflict_reflected_op_prepare_count Integer Global
Ndb_conflict_refresh_op_count Integer Global
Ndb_conflict_trans_conflict_commit_count Integer Global
Ndb_conflict_trans_detect_iter_count Integer Global
Ndb_conflict_trans_reject_count Integer Global
Ndb_conflict_trans_row_conflict_count Integer Global
Ndb_conflict_trans_row_reject_count Integer Global
Ndb_epoch_delete_delete_count Integer Global
Ndb_execute_count Integer Global
Ndb_last_commit_epoch_server Integer Global
Ndb_last_commit_epoch_session Integer Session
Ndb_cluster_node_id Integer Global
Ndb_number_of_data_nodes Integer Global
Ndb_pruned_scan_count Integer Global
Ndb_pushed_queries_defined Integer Global
Ndb_pushed_queries_dropped Integer Global
Ndb_pushed_queries_executed Integer Global
Ndb_pushed_reads Integer Global
Ndb_scan_count Integer Global
Not_flushed_delayed_rows Integer Global
Open_files Integer Global
Open_streams Integer Global
Open_table_definitions Integer Global
Open_tables Integer Both
Opened_files Integer Global
Opened_table_definitions Integer Both
Opened_tables Integer Both
Performance_schema_accounts_lost Integer Global
Performance_schema_cond_classes_lost Integer Global
Performance_schema_cond_instances_lost Integer Global
Performance_schema_digest_lost Integer Global
Performance_schema_file_classes_lost Integer Global
Performance_schema_file_handles_lost Integer Global
Performance_schema_file_instances_lost Integer Global
Performance_schema_hosts_lost Integer Global
Performance_schema_locker_lost Integer Global
Performance_schema_mutex_classes_lost Integer Global
Performance_schema_mutex_instances_lost Integer Global
Performance_schema_rwlock_classes_lost Integer Global
Performance_schema_rwlock_instances_lost Integer Global
Performance_schema_session_connect_attrs_lost Integer Global
Performance_schema_socket_classes_lost Integer Global
Performance_schema_socket_instances_lost Integer Global
Performance_schema_stage_classes_lost Integer Global
Performance_schema_statement_classes_lost Integer Global
Performance_schema_table_handles_lost Integer Global
Performance_schema_table_instances_lost Integer Global
Performance_schema_thread_classes_lost Integer Global
Performance_schema_thread_instances_lost Integer Global
Performance_schema_users_lost Integer Global
Prepared_stmt_count Integer Global
Qcache_free_blocks Integer Global
Qcache_free_memory Integer Global
Qcache_hits Integer Global
Qcache_inserts Integer Global
Qcache_lowmem_prunes Integer Global
Qcache_not_cached Integer Global
Qcache_queries_in_cache Integer Global
Qcache_total_blocks Integer Global
Queries Integer Both
Questions Integer Both
Rpl_semi_sync_master_clients Integer Global
Rpl_semi_sync_master_net_avg_wait_time Integer Global
Rpl_semi_sync_master_net_wait_time Integer Global
Rpl_semi_sync_master_net_waits Integer Global
Rpl_semi_sync_master_no_times Integer Global
Rpl_semi_sync_master_no_tx Integer Global
Rpl_semi_sync_master_status Boolean Global
Rpl_semi_sync_master_timefunc_failures Integer Global
Rpl_semi_sync_master_tx_avg_wait_time Integer Global
Rpl_semi_sync_master_tx_wait_time Integer Global
Rpl_semi_sync_master_tx_waits Integer Global
Rpl_semi_sync_master_wait_pos_backtraverse Integer Global
Rpl_semi_sync_master_wait_sessions Integer Global
Rpl_semi_sync_master_yes_tx Integer Global
Rpl_semi_sync_slave_status Boolean Global
Rsa_public_key String Global
Select_full_join Integer Both
Select_full_range_join Integer Both
Select_range Integer Both
Select_range_check Integer Both
Select_scan Integer Both
Slave_heartbeat_period Numeric Global
Slave_last_heartbeat Datetime Global
Slave_open_temp_tables Integer Global
Slave_received_heartbeats Integer Global
Slave_retried_transactions Integer Global
Slave_rows_last_search_algorithm_used String Global
Slave_running Boolean Global
Slow_launch_threads Integer Both
Slow_queries Integer Both
Sort_merge_passes Integer Both
Sort_range Integer Both
Sort_rows Integer Both
Sort_scan Integer Both
Ssl_accept_renegotiates Integer Global
Ssl_accepts Integer Global
Ssl_callback_cache_hits Integer Global
Ssl_cipher String Both
Ssl_cipher_list String Both
Ssl_client_connects Integer Global
Ssl_connect_renegotiates Integer Global
Ssl_ctx_verify_depth Integer Global
Ssl_ctx_verify_mode Integer Global
Ssl_default_timeout Integer Both
Ssl_finished_accepts Integer Global
Ssl_finished_connects Integer Global
Ssl_server_not_after Integer Both
Ssl_server_not_before Integer Both
Ssl_session_cache_hits Integer Global
Ssl_session_cache_misses Integer Global
Ssl_session_cache_mode String Global
Ssl_session_cache_overflows Integer Global
Ssl_session_cache_size Integer Global
Ssl_session_cache_timeouts Integer Global
Ssl_sessions_reused Integer Both
Ssl_used_session_cache_entries Integer Global
Ssl_verify_depth Integer Both
Ssl_verify_mode Integer Both
Ssl_version String Both
Table_locks_immediate Integer Global
Table_locks_waited Integer Global
Table_open_cache_hits Integer Both
Table_open_cache_misses Integer Both
Table_open_cache_overflows Integer Both
Tc_log_max_pages_used Integer Global
Tc_log_page_size Integer Global
Tc_log_page_waits Integer Global
Threads_cached Integer Global
Threads_connected Integer Global
Threads_created Integer Global
Threads_running Integer Global
Uptime Integer Global
Uptime_since_flush_status Integer Global
validate_password_dictionary_file_last_parsed Datetime Global
validate_password_dictionary_file_words_count Integer Global

5.1.6 Server Command Options

When you start the mysqld server, you can specify program options using any of the methods described in Section 4.2.3, “Specifying Program Options”. The most common methods are to provide options in an option file or on the command line. However, in most cases it is desirable to make sure that the server uses the same options each time it runs. The best way to ensure this is to list them in an option file. See Section 4.2.6, “Using Option Files”. That section also describes option file format and syntax.

mysqld reads options from the [mysqld] and [server] groups. mysqld_safe reads options from the [mysqld], [server], [mysqld_safe], and [safe_mysqld] groups. mysql.server reads options from the [mysqld] and [mysql.server] groups.

An embedded MySQL server usually reads options from the [server], [embedded], and [xxxxx_SERVER] groups, where xxxxx is the name of the application into which the server is embedded.

mysqld accepts many command options. For a brief summary, execute this command:

mysqld --help

To see the full list, use this command:

mysqld --verbose --help

Some of the items in the list are actually system variables that can be set at server startup. These can be displayed at runtime using the SHOW VARIABLES statement. Some items displayed by the preceding mysqld command do not appear in SHOW VARIABLES output; this is because they are options only and not system variables.

The following list shows some of the most common server options. Additional options are described in other sections:

Some options control the size of buffers or caches. For a given buffer, the server might need to allocate internal data structures. These structures typically are allocated from the total memory allocated to the buffer, and the amount of space required might be platform dependent. This means that when you assign a value to an option that controls a buffer size, the amount of space actually available might differ from the value assigned. In some cases, the amount might be less than the value assigned. It is also possible that the server will adjust a value upward. For example, if you assign a value of 0 to an option for which the minimal value is 1024, the server will set the value to 1024.

Values for buffer sizes, lengths, and stack sizes are given in bytes unless otherwise specified.

Some options take file name values. Unless otherwise specified, the default file location is the data directory if the value is a relative path name. To specify the location explicitly, use an absolute path name. Suppose that the data directory is /var/mysql/data. If a file-valued option is given as a relative path name, it will be located under /var/mysql/data. If the value is an absolute path name, its location is as given by the path name.

You can also set the values of server system variables at server startup by using variable names as options. To assign a value to a server system variable, use an option of the form --var_name=value. For example, --key_buffer_size=32M sets the key_buffer_size variable to a value of 32MB.

When you assign a value to a variable, MySQL might automatically correct the value to stay within a given range, or adjust the value to the closest permissible value if only certain values are permitted.

To restrict the maximum value to which a system variable can be set at runtime with the SET statement, specify this maximum by using an option of the form --maximum-var_name=value at server startup.

You can change the values of most system variables at runtime with the SET statement. See Section 13.7.4.1, “SET Syntax for Variable Assignment”.

Section 5.1.7, “Server System Variables”, provides a full description for all variables, and additional information for setting them at server startup and runtime. For information on changing system variables, see Section 5.1.1, “Configuring the Server”.

  • --help, -?

    Property Value
    Command-Line Format --help

    Display a short help message and exit. Use both the --verbose and --help options to see the full message.

  • --allow-suspicious-udfs

    Property Value
    Command-Line Format --allow-suspicious-udfs
    Type Boolean
    Default Value FALSE

    This option controls whether user-defined functions that have only an xxx symbol for the main function can be loaded. By default, the option is off and only UDFs that have at least one auxiliary symbol can be loaded; this prevents attempts at loading functions from shared object files other than those containing legitimate UDFs. See Section 24.4.2.6, “UDF Security Precautions”.

  • --ansi

    Property Value
    Command-Line Format --ansi

    Use standard (ANSI) SQL syntax instead of MySQL syntax. For more precise control over the server SQL mode, use the --sql-mode option instead. See Section 1.7, “MySQL Standards Compliance”, and Section 5.1.10, “Server SQL Modes”.

  • --basedir=dir_name, -b dir_name

    Property Value
    Command-Line Format --basedir=dir_name
    System Variable basedir
    Scope Global
    Dynamic No
    Type Directory name
    Default Value configuration-dependent default

    The path to the MySQL installation directory. This option sets the basedir system variable.

  • --big-tables

    Property Value
    Command-Line Format --big-tables
    System Variable big_tables
    Scope Global, Session
    Dynamic Yes
    Type Boolean
    Default Value OFF

    Enable large result sets by saving all temporary sets in files. This option prevents most table full errors, but also slows down queries for which in-memory tables would suffice. The server is able to handle large result sets automatically by using memory for small temporary tables and switching to disk tables where necessary.

  • --bind-address=addr

    Property Value
    Command-Line Format --bind-address=addr
    System Variable (>= 5.6.1) bind_address
    Scope (>= 5.6.1) Global
    Dynamic (>= 5.6.1) No
    Type String
    Default Value (>= 5.6.6) *
    Default Value (<= 5.6.5) 0.0.0.0

    The MySQL server listens on a single network socket for TCP/IP connections. This socket is bound to a single address, but it is possible for an address to map onto multiple network interfaces. To specify an address, use the --bind-address=addr option at server startup, where addr is an IPv4 or IPv6 address or a host name. If addr is a host name, the server resolves the name to an IP address and binds to that address. If a host name resolves to multiple IP addresses, the server uses the first IPv4 address if there are any, or the first IPv6 address otherwise.

    The server treats different types of addresses as follows:

    • If the address is *, the server accepts TCP/IP connections on all server host IPv4 interfaces, and, if the server host supports IPv6, on all IPv6 interfaces. Use this address to permit both IPv4 and IPv6 connections on all server interfaces. This value is the default.

    • If the address is 0.0.0.0, the server accepts TCP/IP connections on all server host IPv4 interfaces.

    • If the address is ::, the server accepts TCP/IP connections on all server host IPv4 and IPv6 interfaces.

    • If the address is an IPv4-mapped address, the server accepts TCP/IP connections for that address, in either IPv4 or IPv6 format. For example, if the server is bound to ::ffff:127.0.0.1, clients can connect using --host=127.0.0.1 or --host=::ffff:127.0.0.1.

    • If the address is a regular IPv4 or IPv6 address (such as 127.0.0.1 or ::1), the server accepts TCP/IP connections only for that IPv4 or IPv6 address.

    If binding to the address fails, the server produces an error and does not start.

    If you intend to bind the server to a specific address, be sure that the mysql.user system table contains an account with administrative privileges that you can use to connect to that address. Otherwise, you will not be able to shut down the server. For example, if you bind the server to *, you can connect to it using all existing accounts. But if you bind the server to ::1, it accepts connections only on that address. In that case, first make sure that the 'root'@'::1' account is present in the mysql.user table so you can still connect to the server to shut it down.

  • --binlog-format={ROW|STATEMENT|MIXED}

    Property Value
    Command-Line Format --binlog-format=format
    System Variable binlog_format
    Scope Global, Session
    Dynamic Yes
    Type Enumeration
    Default Value (>= 5.6.10-ndb-7.3.1) MIXED
    Default Value STATEMENT
    Valid Values

    ROW

    STATEMENT

    MIXED

    Specify whether to use row-based, statement-based, or mixed replication. Statement-based is the default in MySQL 5.6. See Section 17.1.2, “Replication Formats”.

    Under some conditions, changing this variable at runtime is not possible, or causes replication to fail. See Section 5.4.4.2, “Setting The Binary Log Format”, for more information.

    Setting the binary logging format without enabling binary logging sets the binlog_format global system variable and logs a warning.

  • --bootstrap

    Property Value
    Command-Line Format --bootstrap

    This option is used by the mysql_install_db program to create the MySQL privilege tables without having to start a full MySQL server.

    Replication and global transaction identifiers are automatically disabled whenever this option is used (Bug #13992602). See Section 17.1.3, “Replication with Global Transaction Identifiers”.

    When the server operates in bootstap mode, some functionality is unavailable that limits the statements permitted in any file named by the --init-file option. For more information, see the description of that option.

  • --character-sets-dir=dir_name

    Property Value
    Command-Line Format --character-sets-dir=dir_name
    System Variable character_sets_dir
    Scope Global
    Dynamic No
    Type Directory name

    The directory where character sets are installed. See Section 10.14, “Character Set Configuration”.

  • --character-set-client-handshake

    Property Value
    Command-Line Format --character-set-client-handshake
    Type Boolean
    Default Value TRUE

    Do not ignore character set information sent by the client. To ignore client information and use the default server character set, use --skip-character-set-client-handshake; this makes MySQL behave like MySQL 4.0.

  • --character-set-filesystem=charset_name

    Property Value
    Command-Line Format --character-set-filesystem=name
    System Variable character_set_filesystem
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value binary

    The file system character set. This option sets the character_set_filesystem system variable.

  • --character-set-server=charset_name, -C charset_name

    Property Value
    Command-Line Format --character-set-server
    System Variable character_set_server
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value latin1

    Use charset_name as the default server character set. See Section 10.14, “Character Set Configuration”. If you use this option to specify a nondefault character set, you should also use --collation-server to specify the collation.

  • --chroot=dir_name, -r dir_name

    Property Value
    Command-Line Format --chroot=dir_name
    Type Directory name

    Put the mysqld server in a closed environment during startup by using the chroot() system call. This is a recommended security measure.

    Note

    Use of this option somewhat limits LOAD DATA INFILE and SELECT ... INTO OUTFILE.

  • --collation-server=collation_name

    Property Value
    Command-Line Format --collation-server
    System Variable collation_server
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value latin1_swedish_ci

    Use collation_name as the default server collation. See Section 10.14, “Character Set Configuration”.

  • --console

    Property Value
    Command-Line Format --console
    Platform Specific Windows

    (Windows only.) Write error log messages to stderr and stdout (the console). mysqld does not close the console window if this option is used.

    --log-error takes precedence over --console if both are given.

  • --core-file

    Property Value
    Command-Line Format --core-file
    Type Boolean
    Default Value OFF

    Write a core file if mysqld dies. The name and location of the core file is system dependent. On Linux, a core file named core.pid is written to the current working directory of the process, which for mysqld is the data directory. pid represents the process ID of the server process. On macOS, a core file named core.pid is written to the /cores directory. On Solaris, use the coreadm command to specify where to write the core file and how to name it.

    For some systems, to get a core file you must also specify the --core-file-size option to mysqld_safe. See Section 4.3.2, “mysqld_safe — MySQL Server Startup Script”. On some systems, such as Solaris, you do not get a core file if you are also using the --user option. There might be additional restrictions or limitations. For example, it might be necessary to execute ulimit -c unlimited before starting the server. Consult your system documentation.

  • --datadir=dir_name, -h dir_name

    Property Value
    Command-Line Format --datadir=dir_name
    System Variable datadir
    Scope Global
    Dynamic No
    Type Directory name

    The path to the MySQL server data directory. This option sets the datadir system variable. See the description of that variable.

  • --debug[=debug_options], -# [debug_options]

    Property Value
    Command-Line Format --debug[=debug_options]
    System Variable debug
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value (Windows) d:t:i:O,\mysqld.trace
    Default Value (Unix) d:t:i:o,/tmp/mysqld.trace

    If MySQL is configured with the -DWITH_DEBUG=1 CMake option, you can use this option to get a trace file of what mysqld is doing. A typical debug_options string is d:t:o,file_name. The default is d:t:i:o,/tmp/mysqld.trace on Unix and d:t:i:O,\mysqld.trace on Windows.

    Using -DWITH_DEBUG=1 to configure MySQL with debugging support enables you to use the --debug="d,parser_debug" option when you start the server. This causes the Bison parser that is used to process SQL statements to dump a parser trace to the server's standard error output. Typically, this output is written to the error log.

    This option may be given multiple times. Values that begin with + or - are added to or subtracted from the previous value. For example, --debug=T --debug=+P sets the value to P:T.

    For more information, see Section 24.5.3, “The DBUG Package”.

  • --debug-sync-timeout[=N]

    Property Value
    Command-Line Format --debug-sync-timeout[=#]
    Type Integer

    Controls whether the Debug Sync facility for testing and debugging is enabled. Use of Debug Sync requires that MySQL be configured with the -DENABLE_DEBUG_SYNC=1 CMake option (see Section 2.9.4, “MySQL Source-Configuration Options”). If Debug Sync is not compiled in, this option is not available. The option value is a timeout in seconds. The default value is 0, which disables Debug Sync. To enable it, specify a value greater than 0; this value also becomes the default timeout for individual synchronization points. If the option is given without a value, the timeout is set to 300 seconds.

    For a description of the Debug Sync facility and how to use synchronization points, see MySQL Internals: Test Synchronization.

  • --default-authentication-plugin=plugin_name

    Property Value
    Command-Line Format --default-authentication-plugin=plugin_name
    Introduced 5.6.6
    Type Enumeration
    Default Value mysql_native_password
    Valid Values

    mysql_native_password

    sha256_password

    This option sets the default authentication plugin. These values are permitted:

    Note

    Prior to MySQL 5.6.17, if you use this option to change the default authentication plugin to a value other than mysql_native_password, clients older than MySQL 5.5.7 cannot connect because they do not understand the resulting change to the authentication protocol.

    In MySQL 5.6, there is no server system variable that corresponds to the --default-authentication-plugin option; to read the value set for this option, you must check the running MySQL Server process to see what options, if any, were employed when invoking mysqld (on Linux systems, you can do this with ps ax | grep mysqld or similar), and possibly the server options file as well. This is a known issue which is resolved in MySQL 5.7. (Bug #68858, Bug #16595944)

    The --default-authentication-plugin value affects these aspects of server operation:

    • It determines which authentication plugin the server assigns to new accounts created by CREATE USER and GRANT statements that do not explicitly specify an authentication plugin.

    • The old_passwords system variable affects password hashing for accounts that use the mysql_native_password or sha256_password authentication plugin. If the default authentication plugin is one of those plugins, the server sets old_passwords at startup to the value required by the plugin password hashing method.

    • For an account created with either of the following statements, the server associates the account with the default authentication plugin and assigns the account the given password, hashed as required by that plugin:

      CREATE USER ... IDENTIFIED BY 'cleartext password';
      GRANT ...  IDENTIFIED BY 'cleartext password';
      
    • For an account created with either of the following statements, the server associates the account with the default authentication plugin and assigns the account the given password hash, if the password hash has the format required by the plugin:

      CREATE USER ... IDENTIFIED BY PASSWORD 'encrypted password';
      GRANT ...  IDENTIFIED BY PASSWORD 'encrypted password';
      

      If the password hash is not in the format required by the default authentication plugin, the statement fails.

  • --default-storage-engine=type

    Property Value
    Command-Line Format --default-storage-engine=name
    System Variable default_storage_engine
    Scope Global, Session
    Dynamic Yes
    Type Enumeration
    Default Value InnoDB

    Set the default storage engine for tables. See Chapter 15, Alternative Storage Engines. This option sets the storage engine for permanent tables only. To set the storage engine for TEMPORARY tables, set the default_tmp_storage_engine system variable.

    If you disable the default storage engine at server startup, you must set the default engine for both permanent and TEMPORARY tables to a different engine or the server will not start.

  • --default-time-zone=timezone

    Property Value
    Command-Line Format --default-time-zone=name
    Type String

    Set the default server time zone. This option sets the global time_zone system variable. If this option is not given, the default time zone is the same as the system time zone (given by the value of the system_time_zone system variable.

  • --defaults-extra-file=file_name

    Read this option file after the global option file but (on Unix) before the user option file. If the file does not exist or is otherwise inaccessible, an error occurs. file_name is interpreted relative to the current directory if given as a relative path name rather than a full path name. This must be the first option on the command line if it is used.

    For additional information about this and other option-file options, see Section 4.2.7, “Command-Line Options that Affect Option-File Handling”.

  • --defaults-file=file_name

    Read only the given option file. If the file does not exist or is otherwise inaccessible, an error occurs. file_name is interpreted relative to the current directory if given as a relative path name rather than a full path name.

    Note

    This must be the first option on the command line if it is used, except that if the server is started with the --defaults-file and --install (or --install-manual) options, --install (or --install-manual) must be first.

    For additional information about this and other option-file options, see Section 4.2.7, “Command-Line Options that Affect Option-File Handling”.

  • --defaults-group-suffix=str

    Read not only the usual option groups, but also groups with the usual names and a suffix of str. For example, mysqld normally reads the [mysqld] group. If the --defaults-group-suffix=_other option is given, mysqld also reads the [mysqld_other] group.

    For additional information about this and other option-file options, see Section 4.2.7, “Command-Line Options that Affect Option-File Handling”.

  • --delay-key-write[={OFF|ON|ALL}]

    Property Value
    Command-Line Format --delay-key-write[=name]
    System Variable delay_key_write
    Scope Global
    Dynamic Yes
    Type Enumeration
    Default Value ON
    Valid Values

    ON

    OFF

    ALL

    Specify how to use delayed key writes. Delayed key writing causes key buffers not to be flushed between writes for MyISAM tables. OFF disables delayed key writes. ON enables delayed key writes for those tables that were created with the DELAY_KEY_WRITE option. ALL delays key writes for all MyISAM tables. See Section 5.1.1, “Configuring the Server”, and Section 15.2.1, “MyISAM Startup Options”.

    Note

    If you set this variable to ALL, you should not use MyISAM tables from within another program (such as another MySQL server or myisamchk) when the tables are in use. Doing so leads to index corruption.

  • --des-key-file=file_name

    Property Value
    Command-Line Format --des-key-file=file_name

    Read the default DES keys from this file. These keys are used by the DES_ENCRYPT() and DES_DECRYPT() functions.

  • --enable-named-pipe

    Property Value
    Command-Line Format --enable-named-pipe
    Platform Specific Windows

    Enable support for named pipes. This option applies only on Windows.

  • --engine-condition-pushdown={ON|OFF}

    Property Value
    Command-Line Format --engine-condition-pushdown
    Deprecated Yes (removed in 5.6.1); use optimizer_switch
    System Variable engine_condition_pushdown
    Scope Global, Session
    Dynamic Yes
    Type Boolean
    Default Value ON

    Formerly, this option set the engine_condition_pushdown system variable; the option and the variable were both removed in MySQL 5.6.1. For more information, see Section 8.2.1.4, “Engine Condition Pushdown Optimization”.

  • --event-scheduler[=value]

    Property Value
    Command-Line Format --event-scheduler[=value]
    System Variable event_scheduler
    Scope Global
    Dynamic Yes
    Type Enumeration
    Default Value OFF
    Valid Values

    ON

    OFF

    DISABLED

    Enable or disable, and start or stop, the event scheduler.

    For detailed information, see The --event-scheduler Option.

  • --exit-info[=flags], -T [flags]

    Property Value
    Command-Line Format --exit-info[=flags]
    Type Integer

    This is a bitmask of different flags that you can use for debugging the mysqld server. Do not use this option unless you know exactly what it does!

  • --external-locking

    Property Value
    Command-Line Format --external-locking
    Type Boolean
    Default Value FALSE

    Enable external locking (system locking), which is disabled by default. If you use this option on a system on which lockd does not fully work (such as Linux), it is easy for mysqld to deadlock.

    To disable external locking explicitly, use --skip-external-locking.

    External locking affects only MyISAM table access. For more information, including conditions under which it can and cannot be used, see Section 8.11.5, “External Locking”.

  • --flush

    Property Value
    Command-Line Format --flush
    System Variable flush
    Scope Global
    Dynamic Yes
    Type Boolean
    Default Value OFF

    Flush (synchronize) all changes to disk after each SQL statement. Normally, MySQL does a write of all changes to disk only after each SQL statement and lets the operating system handle the synchronizing to disk. See Section B.5.3.3, “What to Do If MySQL Keeps Crashing”.

    Note

    If --flush is specified, the value of flush_time does not matter and changes to flush_time have no effect on flush behavior.

  • --gdb

    Property Value
    Command-Line Format --gdb
    Type Boolean
    Default Value FALSE

    Install an interrupt handler for SIGINT (needed to stop mysqld with ^C to set breakpoints) and disable stack tracing and core file handling. See Section 24.5, “Debugging and Porting MySQL”.

  • --general-log[={0|1}]

    Property Value
    Command-Line Format --general-log
    System Variable general_log
    Scope Global
    Dynamic Yes
    Type Boolean
    Default Value OFF

    Specify the initial general query log state. With no argument or an argument of 1, the --general-log option enables the log. If omitted or given with an argument of 0, the option disables the log.

  • --ignore-db-dir=dir_name

    Property Value
    Command-Line Format --ignore-db-dir
    Introduced 5.6.3
    Type Directory name

    This option tells the server to ignore the given directory name for purposes of the SHOW DATABASES statement or INFORMATION_SCHEMA tables. For example, if a MySQL configuration locates the data directory at the root of a file system on Unix, the system might create a lost+found directory there that the server should ignore. Starting the server with --ignore-db-dir=lost+found causes that name not to be listed as a database.

    To specify more than one name, use this option multiple times, once for each name. Specifying the option with an empty value (that is, as --ignore-db-dir=) resets the directory list to the empty list.

    Instances of this option given at server startup are used to set the ignore_db_dirs system variable.

  • --init-file=file_name

    Property Value
    Command-Line Format --init-file=file_name
    System Variable init_file
    Scope Global
    Dynamic No
    Type File name

    Read SQL statements from this file at startup. Each statement must be on a single line and should not include comments.

    If the server is started with the --bootstrap option, it operates in bootstap mode and some functionality is unavailable that limits the statements permitted in the file. These include statements that relate to account management (such as CREATE USER or GRANT), replication, and global transaction identifiers. See Section 17.1.3, “Replication with Global Transaction Identifiers”.

  • --innodb-xxx

    Set an option for the InnoDB storage engine. The InnoDB options are listed in Section 14.14, “InnoDB Startup Options and System Variables”.

  • --install [service_name]

    Property Value
    Command-Line Format --install [service_name]
    Platform Specific Windows

    (Windows only) Install the server as a Windows service that starts automatically during Windows startup. The default service name is MySQL if no service_name value is given. For more information, see Section 2.3.5.7, “Starting MySQL as a Windows Service”.

    Note

    If the server is started with the --defaults-file and --install options, --install must be first.

  • --install-manual [service_name]

    Property Value
    Command-Line Format --install-manual [service_name]
    Platform Specific Windows

    (Windows only) Install the server as a Windows service that must be started manually. It does not start automatically during Windows startup. The default service name is MySQL if no service_name value is given. For more information, see Section 2.3.5.7, “Starting MySQL as a Windows Service”.

    Note

    If the server is started with the --defaults-file and --install-manual options, --install-manual must be first.

  • --language=lang_name, -L lang_name

    Property Value
    Command-Line Format --language=name
    Deprecated 5.6.1; use lc-messages-dir
    System Variable language
    Scope Global
    Dynamic No
    Type Directory name
    Default Value /usr/local/mysql/share/mysql/english/

    The language to use for error messages. lang_name can be given as the language name or as the full path name to the directory where the language files are installed. See Section 10.11, “Setting the Error Message Language”.

    --lc-messages-dir and --lc-messages should be used rather than --language, which is deprecated and handled as an alias for --lc-messages-dir. The --language option will be removed in a future MySQL release.

  • --large-pages

    Property Value
    Command-Line Format --large-pages
    System Variable large_pages
    Scope Global
    Dynamic No
    Platform Specific Linux
    Type Boolean
    Default Value FALSE

    Some hardware/operating system architectures support memory pages greater than the default (usually 4KB). The actual implementation of this support depends on the underlying hardware and operating system. Applications that perform a lot of memory accesses may obtain performance improvements by using large pages due to reduced Translation Lookaside Buffer (TLB) misses.

    MySQL supports the Linux implementation of large page support (which is called HugeTLB in Linux). See Section 8.12.4.2, “Enabling Large Page Support”. For Solaris support of large pages, see the description of the --super-large-pages option.

    --large-pages is disabled by default.

  • --lc-messages=locale_name

    Property Value
    Command-Line Format --lc-messages=name
    System Variable lc_messages
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value en_US

    The locale to use for error messages. The default is en_US. The server converts the argument to a language name and combines it with the value of --lc-messages-dir to produce the location for the error message file. See Section 10.11, “Setting the Error Message Language”.

  • --lc-messages-dir=dir_name

    Property Value
    Command-Line Format --lc-messages-dir=dir_name
    System Variable lc_messages_dir
    Scope Global
    Dynamic No
    Type Directory name

    The directory where error messages are located. The server uses the value together with the value of --lc-messages to produce the location for the error message file. See Section 10.11, “Setting the Error Message Language”.

  • --local-service

    Property Value
    Command-Line Format --local-service

    (Windows only) A --local-service option following the service name causes the server to run using the LocalService Windows account that has limited system privileges. If both --defaults-file and --local-service are given following the service name, they can be in any order. See Section 2.3.5.7, “Starting MySQL as a Windows Service”.

  • --log[=file_name], -l [file_name]

    Property Value
    Command-Line Format --log[=file_name]
    Deprecated Yes (removed in 5.6.1); use general-log
    System Variable log
    Scope Global
    Dynamic Yes
    Type File name

    The --log option was removed in MySQL 5.6.1 (along with the log system variable). Instead, use the --general_log option to enable the general query log and the --general_log_file=file_name option to set the general query log file name.

  • --log-error[=file_name]

    Property Value
    Command-Line Format --log-error[=file_name]
    System Variable log_error
    Scope Global
    Dynamic No
    Type File name

    Write the error log and startup messages to this file. See Section 5.4.2, “The Error Log”.

    If the option names no file, the error log file name on Unix and Unix-like systems is host_name.err in the data directory. The file name on Windows is the same, unless the --pid-file option is specified. In that case, the file name is the PID file base name with a suffix of .err in the data directory.

    If the option names a file, the error log file has that name (with an .err suffix added if the name has no suffix), located under the data directory unless an absolute path name is given to specify a different location.

    On Windows, --log-error takes precedence over --console if both are given.

  • --log-isam[=file_name]

    Property Value
    Command-Line Format --log-isam[=file_name]
    Type File name

    Log all MyISAM changes to this file (used only when debugging MyISAM).

  • --log-queries-not-using-indexes

    Property Value
    Command-Line Format --log-queries-not-using-indexes
    System Variable log_queries_not_using_indexes
    Scope Global
    Dynamic Yes
    Type Boolean
    Default Value OFF

    If you are using this option with the slow query log enabled, queries that are expected to retrieve all rows are logged. See Section 5.4.5, “The Slow Query Log”. This option does not necessarily mean that no index is used. For example, a query that uses a full index scan uses an index but would be logged because the index would not limit the number of rows.

  • --log-raw

    Property Value
    Command-Line Format --log-raw[=value]
    Introduced 5.6.3
    Type Boolean
    Default Value OFF

    Passwords in certain statements written to the general query log, slow query log, and binary log are rewritten by the server not to occur literally in plain text. Password rewriting can be suppressed for the general query log by starting the server with the --log-raw option. This option may be useful for diagnostic purposes, to see the exact text of statements as received by the server, but for security reasons is not recommended for production use.

  • --log-short-format

    Property Value
    Command-Line Format --log-short-format
    Type Boolean
    Default Value FALSE

    Log less information to the slow query log, if it has been activated.

  • --log-slow-admin-statements

    Property Value
    Command-Line Format --log-slow-admin-statements (<= 5.6.10)
    Removed 5.6.11
    Type Boolean
    Default Value OFF

    Include slow administrative statements in the statements written to the slow query log. Administrative statements include ALTER TABLE, ANALYZE TABLE, CHECK TABLE, CREATE INDEX, DROP INDEX, OPTIMIZE TABLE, and REPAIR TABLE.

    This command-line option was removed in MySQL 5.6.11 and replaced by the log_slow_admin_statements system variable. The system variable can be set on the command line or in option files the same way as the option, so there is no need for any changes at server startup, but the system variable also makes it possible to examine or set the value at runtime.

  • --log-slow-queries[=file_name]

    Property Value
    Command-Line Format --log-slow-queries[=name]
    Deprecated Yes (removed in 5.6.1); use slow-query-log
    System Variable log_slow_queries
    Scope Global
    Dynamic Yes
    Type Boolean

    The --log-slow-queries option was removed in MySQL 5.6.1 (along with the log_slow_queries system variable). Instead, use the --slow_query_log option to enable the slow query log and the --slow_query_log_file=file_name option to set the slow query log file name.

  • --log-tc=file_name

    Property Value
    Command-Line Format --log-tc=file_name
    Type File name
    Default Value tc.log

    The name of the memory-mapped transaction coordinator log file (for XA transactions that affect multiple storage engines when the binary log is disabled). The default name is tc.log. The file is created under the data directory if not given as a full path name. This option is unused.

  • --log-tc-size=size

    Property Value
    Command-Line Format --log-tc-size=#
    Type Integer
    Default Value 24576
    Maximum Value (64-bit platforms) 18446744073709551615
    Maximum Value (32-bit platforms) 4294967295

    The size in bytes of the memory-mapped transaction coordinator log. The default size is 24KB.

  • --log-warnings[=level], -W [level]

    Property Value
    Command-Line Format --log-warnings[=#]
    System Variable log_warnings
    Scope (>= 5.6.4) Global
    Scope (<= 5.6.3) Global, Session
    Dynamic Yes
    Type Integer
    Default Value 1
    Minimum Value 0
    Maximum Value (64-bit platforms) 18446744073709551615
    Maximum Value (32-bit platforms) 4294967295

    Print out warnings such as Aborted connection... to the error log. This option is enabled (1) by default. To disable it, use --log-warnings=0. Specifying the option without a level value increments the current value by 1. Enabling this option by setting it greater than 0 is recommended, for example, if you use replication (you get more information about what is happening, such as messages about network failures and reconnections). If the value is greater than 1, aborted connections are written to the error log, and access-denied errors for new connection attempts are written. See Section B.5.2.11, “Communication Errors and Aborted Connections”.

    If a slave server was started with --log-warnings enabled, the slave prints messages to the error log to provide information about its status, such as the binary log and relay log coordinates where it starts its job, when it is switching to another relay log, when it reconnects after a disconnect, and so forth. The server logs messages about statements that are unsafe for statement-based logging if --log-warnings is greater than 0.

  • --low-priority-updates

    Property Value
    Command-Line Format --low-priority-updates
    System Variable low_priority_updates
    Scope Global, Session
    Dynamic Yes
    Type Boolean
    Default Value FALSE

    Give table-modifying operations (INSERT, REPLACE, DELETE, UPDATE) lower priority than selects. This can also be done using {INSERT | REPLACE | DELETE | UPDATE} LOW_PRIORITY ... to lower the priority of only one query, or by SET LOW_PRIORITY_UPDATES=1 to change the priority in one thread. This affects only storage engines that use only table-level locking (MyISAM, MEMORY, MERGE). See Section 8.11.2, “Table Locking Issues”.

  • --min-examined-row-limit=number

    Property Value
    Command-Line Format --min-examined-row-limit=#
    System Variable min_examined_row_limit
    Scope Global, Session
    Dynamic Yes
    Type Integer
    Default Value 0
    Minimum Value 0
    Maximum Value (64-bit platforms) 18446744073709551615
    Maximum Value (32-bit platforms) 4294967295

    When this option is set, queries which examine fewer than number rows are not written to the slow query log. The default is 0.

  • --memlock

    Property Value
    Command-Line Format --memlock
    Type Boolean
    Default Value FALSE

    Lock the mysqld process in memory. This option might help if you have a problem where the operating system is causing mysqld to swap to disk.

    --memlock works on systems that support the mlockall() system call; this includes Solaris, most Linux distributions that use a 2.4 or higher kernel, and perhaps other Unix systems. On Linux systems, you can tell whether or not mlockall() (and thus this option) is supported by checking to see whether or not it is defined in the system mman.h file, like this:

    shell> grep mlockall /usr/include/sys/mman.h
    

    If mlockall() is supported, you should see in the output of the previous command something like the following:

    extern int mlockall (int __flags) __THROW;
    
    Important

    Use of this option may require you to run the server as root, which, for reasons of security, is normally not a good idea. See Section 6.1.5, “How to Run MySQL as a Normal User”.

    On Linux and perhaps other systems, you can avoid the need to run the server as root by changing the limits.conf file. See the notes regarding the memlock limit in Section 8.12.4.2, “Enabling Large Page Support”.

    You must not try to use this option on a system that does not support the mlockall() system call; if you do so, mysqld will very likely crash as soon as you try to start it.

  • --myisam-block-size=N

    Property Value
    Command-Line Format --myisam-block-size=#
    Type Integer
    Default Value 1024
    Minimum Value 1024
    Maximum Value 16384

    The block size to be used for MyISAM index pages.

  • --myisam-recover-options[=option[,option]...]]

    Property Value
    Command-Line Format --myisam-recover-options[=name]
    Type Enumeration
    Default Value OFF
    Valid Values

    OFF

    DEFAULT

    BACKUP

    FORCE

    QUICK

    Set the MyISAM storage engine recovery mode. The option value is any combination of the values of OFF, DEFAULT, BACKUP, FORCE, or QUICK. If you specify multiple values, separate them by commas. Specifying the option with no argument is the same as specifying DEFAULT, and specifying with an explicit value of "" disables recovery (same as a value of OFF). If recovery is enabled, each time mysqld opens a MyISAM table, it checks whether the table is marked as crashed or was not closed properly. (The last option works only if you are running with external locking disabled.) If this is the case, mysqld runs a check on the table. If the table was corrupted, mysqld attempts to repair it.

    The following options affect how the repair works.

    Option Description
    OFF No recovery.
    DEFAULT Recovery without backup, forcing, or quick checking.
    BACKUP If the data file was changed during recovery, save a backup of the tbl_name.MYD file as tbl_name-datetime.BAK.
    FORCE Run recovery even if we would lose more than one row from the .MYD file.
    QUICK Do not check the rows in the table if there are not any delete blocks.

    Before the server automatically repairs a table, it writes a note about the repair to the error log. If you want to be able to recover from most problems without user intervention, you should use the options BACKUP,FORCE. This forces a repair of a table even if some rows would be deleted, but it keeps the old data file as a backup so that you can later examine what happened.

    See Section 15.2.1, “MyISAM Startup Options”.

  • --no-defaults

    Do not read any option files. If program startup fails due to reading unknown options from an option file, --no-defaults can be used to prevent them from being read. This must be the first option on the command line if it is used.

    For additional information about this and other option-file options, see Section 4.2.7, “Command-Line Options that Affect Option-File Handling”.

  • --old-alter-table

    Property Value
    Command-Line Format --old-alter-table
    System Variable old_alter_table
    Scope Global, Session
    Dynamic Yes
    Type Boolean
    Default Value OFF

    When this option is given, the server does not use the optimized method of processing an ALTER TABLE operation. It reverts to using a temporary table, copying over the data, and then renaming the temporary table to the original, as used by MySQL 5.0 and earlier. For more information on the operation of ALTER TABLE, see Section 13.1.7, “ALTER TABLE Syntax”.

  • --old-style-user-limits

    Property Value
    Command-Line Format --old-style-user-limits
    Type Boolean
    Default Value FALSE

    Enable old-style user limits. (Before MySQL 5.0.3, account resource limits were counted separately for each host from which a user connected rather than per account row in the user table.) See Section 6.3.4, “Setting Account Resource Limits”.

  • --one-thread

    Property Value
    Command-Line Format --one-thread
    Removed 5.6.1

    This option was removed in MySQL 5.6.1. Use --thread_handling=no-threads instead.

  • --open-files-limit=count

    Property Value
    Command-Line Format --open-files-limit=#
    System Variable open_files_limit
    Scope Global
    Dynamic No
    Type Integer
    Default Value (>= 5.6.8) 5000, with possible adjustment
    Default Value (<= 5.6.7) 0
    Minimum Value 0
    Maximum Value platform dependent

    Changes the number of file descriptors available to mysqld. You should try increasing the value of this option if mysqld gives you the error Too many open files. mysqld uses the option value to reserve descriptors with setrlimit(). Internally, the maximum value for this option is the maximum unsigned integer value, but the actual maximum is platform dependent. If the requested number of file descriptors cannot be allocated, mysqld writes a warning to the error log.

    mysqld may attempt to allocate more than the requested number of descriptors (if they are available), using the values of max_connections and table_open_cache to estimate whether more descriptors will be needed.

    On Unix, the value cannot be set greater than ulimit -n.

  • --partition[=value]

    Property Value
    Command-Line Format --partition
    Disabled by skip-partition
    Type Boolean
    Default Value ON

    Enables or disables user-defined partitioning support in the MySQL Server.

  • --performance-schema-xxx

    Configure a Performance Schema option. For details, see Section 22.14, “Performance Schema Command Options”.

  • --pid-file=file_name

    Property Value
    Command-Line Format --pid-file=file_name
    System Variable pid_file
    Scope Global
    Dynamic No
    Type File name

    The path name of the process ID file. The server creates the file in the data directory unless an absolute path name is given to specify a different directory. If you specify this option, you must specify a value. If you do not specify this option, MySQL uses a default value of host_name.pid, where host_name is the name of the host machine.

    The process ID file is used by other programs such as mysqld_safe to determine the server's process ID. On Windows, this variable also affects the default error log file name. See Section 5.4.2, “The Error Log”.

  • --plugin-xxx

    Specifies an option that pertains to a server plugin. For example, many storage engines can be built as plugins, and for such engines, options for them can be specified with a --plugin prefix. Thus, the --innodb_file_per_table option for InnoDB can be specified as --plugin-innodb_file_per_table.

    For boolean options that can be enabled or disabled, the --skip prefix and other alternative formats are supported as well (see Section 4.2.5, “Program Option Modifiers”). For example, --skip-plugin-innodb_file_per_table disables innodb_file_per_table.

    The rationale for the --plugin prefix is that it enables plugin options to be specified unambiguously if there is a name conflict with a built-in server option. For example, were a plugin writer to name a plugin sql and implement a mode option, the option name might be --sql-mode, which would conflict with the built-in option of the same name. In such cases, references to the conflicting name are resolved in favor of the built-in option. To avoid the ambiguity, users can specify the plugin option as --plugin-sql-mode. Use of the --plugin prefix for plugin options is recommended to avoid any question of ambiguity.

  • --plugin-load=plugin_list

    Property Value
    Command-Line Format --plugin-load=plugin_list
    Type String

    This option tells the server to load the named plugins at startup. If multiple --plugin-load options are given, only the last one is used. Additional plugins to load may be specified using --plugin-load-add options.

    The option value is a semicolon-separated list of name=plugin_library and plugin_library values. Each name is the name of a plugin to load, and plugin_library is the name of the library file that contains the plugin code. If a plugin library is named without any preceding plugin name, the server loads all plugins in the library. The server looks for plugin library files in the directory named by the plugin_dir system variable.

    For example, if plugins named myplug1 and myplug2 have library files myplug1.so and myplug2.so, use this option to perform an early plugin load:

    shell> mysqld --plugin-load="myplug1=myplug1.so;myplug2=myplug2.so"
    

    Quotes are used around the argument value here because otherwise semicolon (;) is interpreted as a special character by some command interpreters. (Unix shells treat it as a command terminator, for example.)

    Each named plugin is loaded for a single invocation of mysqld only. After a restart, the plugin is not loaded unless --plugin-load is used again. This is in contrast to INSTALL PLUGIN, which adds an entry to the mysql.plugins table to cause the plugin to be loaded for every normal server startup.

    Under normal startup, the server determines which plugins to load by reading the mysql.plugins system table. If the server is started with the --skip-grant-tables option, it does not consult the mysql.plugins table and does not load plugins listed there. --plugin-load enables plugins to be loaded even when --skip-grant-tables is given. --plugin-load also enables plugins to be loaded at startup that cannot be loaded at runtime.

    For additional information about plugin loading, see Section 5.5.1, “Installing and Uninstalling Plugins”.

  • --plugin-load-add=plugin_list

    Property Value
    Command-Line Format --plugin-load-add=plugin_list
    Introduced 5.6.3
    Type String

    This option complements the --plugin-load option. --plugin-load-add adds a plugin or plugins to the set of plugins to be loaded at startup. The argument format is the same as for --plugin-load. --plugin-load-add can be used to avoid specifying a large set of plugins as a single long unwieldy --plugin-load argument.

    --plugin-load-add can be given in the absence of --plugin-load, but any instance of --plugin-load-add that appears before --plugin-load. has no effect because --plugin-load resets the set of plugins to load. In other words, these options:

    --plugin-load=x --plugin-load-add=y
    

    are equivalent to this option:

    --plugin-load="x;y"
    

    But these options:

    --plugin-load-add=y --plugin-load=x
    

    are equivalent to this option:

    --plugin-load=x
    

    For additional information about plugin loading, see Section 5.5.1, “Installing and Uninstalling Plugins”.

  • --port=port_num, -P port_num

    Property Value
    Command-Line Format --port=#
    System Variable port
    Scope Global
    Dynamic No
    Type Integer
    Default Value 3306
    Minimum Value 0
    Maximum Value 65535

    The port number to use when listening for TCP/IP connections. On Unix and Unix-like systems, the port number must be 1024 or higher unless the server is started by the root system user. Setting this option to 0 causes the default value to be used.

  • --port-open-timeout=num

    Property Value
    Command-Line Format --port-open-timeout=#
    Type Integer
    Default Value 0

    On some systems, when the server is stopped, the TCP/IP port might not become available immediately. If the server is restarted quickly afterward, its attempt to reopen the port can fail. This option indicates how many seconds the server should wait for the TCP/IP port to become free if it cannot be opened. The default is not to wait.

  • --print-defaults

    Print the program name and all options that it gets from option files. This must be the first option on the command line if it is used, except that it may be used immediately after --defaults-file or --defaults-extra-file.

    For additional information about this and other option-file options, see Section 4.2.7, “Command-Line Options that Affect Option-File Handling”.

  • --remove [service_name]

    Property Value
    Command-Line Format --remove [service_name]
    Platform Specific Windows

    (Windows only) Remove a MySQL Windows service. The default service name is MySQL if no service_name value is given. For more information, see Section 2.3.5.7, “Starting MySQL as a Windows Service”.

  • --safe-mode

    Property Value
    Command-Line Format --safe-mode
    Deprecated Yes (removed in 5.6.6)

    Skip some optimization stages. This option was removed in MySQL 5.6.6.

  • --safe-user-create

    Property Value
    Command-Line Format --safe-user-create
    Type Boolean
    Default Value FALSE

    If this option is enabled, a user cannot create new MySQL users by using the GRANT statement unless the user has the INSERT privilege for the mysql.user system table or any column in the table. If you want a user to have the ability to create new users that have those privileges that the user has the right to grant, you should grant the user the following privilege:

    GRANT INSERT(user) ON mysql.user TO 'user_name'@'host_name';
    

    This ensures that the user cannot change any privilege columns directly, but has to use the GRANT statement to give privileges to other users.

  • --secure-auth

    Property Value
    Command-Line Format --secure-auth
    System Variable secure_auth
    Scope Global
    Dynamic Yes
    Type Boolean
    Default Value (>= 5.6.5) ON
    Default Value (<= 5.6.4) OFF

    This option causes the server to block connections by clients that attempt to use accounts that have passwords stored in the old (pre-4.1) format. Use it to prevent all use of passwords employing the old format (and hence insecure communication over the network). This option is enabled by default; to disable it, use --skip-secure-auth.

    Server startup fails with an error if this option is enabled and the privilege tables are in pre-4.1 format. See Section B.5.2.4, “Client does not support authentication protocol”.

    The mysql client also has a --secure-auth option, which prevents connections to a server if the server requires a password in old format for the client account.

    Note

    Passwords that use the pre-4.1 hashing method are less secure than passwords that use the native password hashing method and should be avoided. Pre-4.1 passwords are deprecated and support for them will be removed in a future MySQL release. Consequently, disabling secure authentication using --skip-secure-auth is also deprecated.

  • --secure-file-priv=dir_name

    Property Value
    Command-Line Format --secure-file-priv=dir_name
    System Variable secure_file_priv
    Scope Global
    Dynamic No
    Type String
    Default Value (>= 5.6.34) platform specific
    Default Value (<= 5.6.33) empty string
    Valid Values (>= 5.6.34)

    empty string

    dirname

    NULL

    Valid Values (<= 5.6.33)

    empty string

    dirname

    This option sets the secure_file_priv system variable, which is used to limit the effect of data import and export operations, such as those performed by the LOAD DATA and SELECT ... INTO OUTFILE statements and the LOAD_FILE() function. For more information, see the description of secure_file_priv.

  • --shared-memory

    Property Value
    Command-Line Format --shared-memory[={0,1}]
    System Variable shared_memory
    Scope Global
    Dynamic No
    Platform Specific Windows
    Type Boolean
    Default Value FALSE

    Enable shared-memory connections by local clients. This option is available only on Windows.

  • --shared-memory-base-name=name

    Property Value
    Command-Line Format --shared-memory-base-name=name
    System Variable shared_memory_base_name
    Scope Global
    Dynamic No
    Platform Specific Windows
    Type String
    Default Value MYSQL

    The name of shared memory to use for shared-memory connections. This option is available only on Windows. The default name is MYSQL. The name is case sensitive.

  • --skip-concurrent-insert

    Turn off the ability to select and insert at the same time on MyISAM tables. (This is to be used only if you think you have found a bug in this feature.) See Section 8.11.3, “Concurrent Inserts”.

  • --skip-event-scheduler

    Property Value
    Command-Line Format

    --skip-event-scheduler

    --disable-event-scheduler

    Turns the Event Scheduler OFF. This is not the same as disabling the Event Scheduler, which requires setting --event-scheduler=DISABLED; see The --event-scheduler Option, for more information.

  • --skip-grant-tables

    Property Value
    Command-Line Format --skip-grant-tables
    Type Boolean
    Default Value FALSE

    This option causes the server to start without using the privilege system at all, which gives anyone with access to the server unrestricted access to all databases. You can cause a running server to start using the grant tables again by executing mysqladmin flush-privileges or mysqladmin reload command from a system shell, or by issuing a MySQL FLUSH PRIVILEGES statement after connecting to the server.

    This option also causes the server to suppress during its startup sequence the loading of user-defined functions (UDFs), scheduled events, and plugins that were installed with the INSTALL PLUGIN statement. To cause plugins to be loaded anyway, use the --plugin-load option.

    FLUSH PRIVILEGES might be executed implicitly by other actions performed after startup. For example, mysql_upgrade flushes the privileges during the upgrade procedure.

  • --skip-host-cache

    Property Value
    Command-Line Format --skip-host-cache

    Disable use of the internal host cache for faster name-to-IP resolution. With the cache disabled, the server performs a DNS lookup every time a client connects.

    Use of --skip-host-cache is similar to setting the host_cache_size system variable to 0, but host_cache_size is more flexible because it can also be used to resize, enable, or disable the host cache at runtime, not just at server startup.

    If you start the server with --skip-host-cache, that does not prevent changes to the value of host_cache_size, but such changes have no effect and the cache is not re-enabled even if host_cache_size is set larger than 0.

    For more information about how the host cache works, see Section 8.12.5.2, “DNS Lookup Optimization and the Host Cache”.

  • --skip-innodb

    Disable the InnoDB storage engine. In this case, because the default storage engine is InnoDB, the server will not start unless you also use --default-storage-engine and --default-tmp-storage-engine to set the default to some other engine for both permanent and TEMPORARY tables.

    As of MySQL 5.6.21, the --skip-innodb option is deprecated. Its use results in a warning. This option will be removed in a future MySQL release.

  • --skip-name-resolve

    Property Value
    Command-Line Format --skip-name-resolve
    System Variable skip_name_resolve
    Scope Global
    Dynamic No
    Type Boolean
    Default Value OFF

    Do not resolve host names when checking client connections. Use only IP addresses. If you use this option, all Host column values in the grant tables must be IP addresses or localhost. See Section 8.12.5.2, “DNS Lookup Optimization and the Host Cache”.

    Depending on the network configuration of your system and the Host values for your accounts, clients may need to connect using an explicit --host option, such as --host=localhost, --host=127.0.0.1, or --host=::1.

    An attempt to connect to the host 127.0.0.1 normally resolves to the localhost account. However, this fails if the server is run with the --skip-name-resolve option, so make sure that an account exists that can accept a connection. For example, to be able to connect as root using --host=127.0.0.1 or --host=::1, create these accounts:

    CREATE USER 'root'@'127.0.0.1' IDENTIFIED BY 'root-password';
    CREATE USER 'root'@'::1' IDENTIFIED BY 'root-password';
    
  • --skip-networking

    Property Value
    Command-Line Format --skip-networking
    System Variable skip_networking
    Scope Global
    Dynamic No

    Do not listen for TCP/IP connections at all. All interaction with mysqld must be made using named pipes or shared memory (on Windows) or Unix socket files (on Unix). This option is highly recommended for systems where only local clients are permitted. See Section 8.12.5.2, “DNS Lookup Optimization and the Host Cache”.

  • --skip-partition

    Property Value
    Command-Line Format

    --skip-partition

    --disable-partition

    Disables user-defined partitioning. Partitioned tables can be seen using SHOW TABLES or by querying the INFORMATION_SCHEMA.TABLES table, but cannot be created or modified, nor can data in such tables be accessed. All partition-specific columns in the INFORMATION_SCHEMA.PARTITIONS table display NULL.

    Since DROP TABLE removes table definition (.frm) files, this statement works on partitioned tables even when partitioning is disabled using the option. The statement, however, does not remove .par files associated with partitioned tables in such cases. For this reason, you should avoid dropping partitioned tables with partitioning disabled, or take action to remove the orphaned .par files manually.

  • --ssl*

    Options that begin with --ssl specify whether to permit clients to connect using SSL and indicate where to find SSL keys and certificates. See Section 6.4.2, “Command Options for Encrypted Connections”.

  • --standalone

    Property Value
    Command-Line Format --standalone
    Platform Specific Windows

    Available on Windows only; instructs the MySQL server not to run as a service.

  • --super-large-pages

    Property Value
    Command-Line Format --super-large-pages
    Platform Specific Solaris
    Type Boolean
    Default Value FALSE

    Standard use of large pages in MySQL attempts to use the largest size supported, up to 4MB. Under Solaris, a super large pages feature enables uses of pages up to 256MB. This feature is available for recent SPARC platforms. It can be enabled or disabled by using the --super-large-pages or --skip-super-large-pages option.

  • --symbolic-links, --skip-symbolic-links

    Property Value
    Command-Line Format --symbolic-links
    Type Boolean
    Default Value ON

    Enable or disable symbolic link support. This option has different effects on Windows and Unix:

  • --skip-show-database

    Property Value
    Command-Line Format --skip-show-database
    System Variable skip_show_database
    Scope Global
    Dynamic No

    This option sets the skip_show_database system variable that controls who is permitted to use the SHOW DATABASES statement. See Section 5.1.7, “Server System Variables”.

  • --skip-stack-trace

    Property Value
    Command-Line Format --skip-stack-trace

    Do not write stack traces. This option is useful when you are running mysqld under a debugger. On some systems, you also must use this option to get a core file. See Section 24.5, “Debugging and Porting MySQL”.

  • --skip-thread-priority

    Property Value
    Command-Line Format --skip-thread-priority
    Deprecated Yes (removed in 5.6.1)

    Disable using thread priorities for faster response time. This option was unused and was removed in MySQL 5.6.1.

  • --slow-query-log[={0|1}]

    Property Value
    Command-Line Format --slow-query-log
    System Variable slow_query_log
    Scope Global
    Dynamic Yes
    Type Boolean
    Default Value OFF

    Specify the initial slow query log state. With no argument or an argument of 1, the --slow-query-log option enables the log. If omitted or given with an argument of 0, the option disables the log.

  • --slow-start-timeout=timeout

    Property Value
    Command-Line Format --slow-start-timeout=#
    Introduced 5.6.5
    Type Integer
    Default Value 15000

    This option controls the Windows service control manager's service start timeout. The value is the maximum number of milliseconds that the service control manager waits before trying to kill the windows service during startup. The default value is 15000 (15 seconds). If the MySQL service takes too long to start, you may need to increase this value. A value of 0 means there is no timeout.

  • --socket=path

    Property Value
    Command-Line Format --socket={file_name|pipe_name}
    System Variable socket
    Scope Global
    Dynamic No
    Type String
    Default Value (Other) /tmp/mysql.sock
    Default Value (Windows) MySQL

    On Unix, this option specifies the Unix socket file to use when listening for local connections. The default value is /tmp/mysql.sock. If this option is given, the server creates the file in the data directory unless an absolute path name is given to specify a different directory. On Windows, the option specifies the pipe name to use when listening for local connections that use a named pipe. The default value is MySQL (not case sensitive).

  • --sql-mode=value[,value[,value...]]

    Property Value
    Command-Line Format --sql-mode=name
    System Variable sql_mode
    Scope Global, Session
    Dynamic Yes
    Type Set
    Default Value (>= 5.6.6) NO_ENGINE_SUBSTITUTION
    Default Value (<= 5.6.5) ''
    Valid Values

    ALLOW_INVALID_DATES

    ANSI_QUOTES

    ERROR_FOR_DIVISION_BY_ZERO

    HIGH_NOT_PRECEDENCE

    IGNORE_SPACE

    NO_AUTO_CREATE_USER

    NO_AUTO_VALUE_ON_ZERO

    NO_BACKSLASH_ESCAPES

    NO_DIR_IN_CREATE

    NO_ENGINE_SUBSTITUTION

    NO_FIELD_OPTIONS

    NO_KEY_OPTIONS

    NO_TABLE_OPTIONS

    NO_UNSIGNED_SUBTRACTION

    NO_ZERO_DATE

    NO_ZERO_IN_DATE

    ONLY_FULL_GROUP_BY

    PAD_CHAR_TO_FULL_LENGTH

    PIPES_AS_CONCAT

    REAL_AS_FLOAT

    STRICT_ALL_TABLES

    STRICT_TRANS_TABLES

    Set the SQL mode. The default is NO_ENGINE_SUBSTITUTION. See Section 5.1.10, “Server SQL Modes”.

    Note

    MySQL installation programs may configure the SQL mode during the installation process. For example, mysql_install_db creates a default option file named my.cnf in the base installation directory. This file contains a line that sets the SQL mode; see Section 4.4.3, “mysql_install_db — Initialize MySQL Data Directory”.

    If the SQL mode differs from the default or from what you expect, check for a setting in an option file that the server reads at startup.

  • --sysdate-is-now

    Property Value
    Command-Line Format --sysdate-is-now
    Type Boolean
    Default Value FALSE

    SYSDATE() by default returns the time at which it executes, not the time at which the statement in which it occurs begins executing. This differs from the behavior of NOW(). This option causes SYSDATE() to be an alias for NOW(). For information about the implications for binary logging and replication, see the description for SYSDATE() in Section 12.7, “Date and Time Functions” and for SET TIMESTAMP in Section 5.1.7, “Server System Variables”.

  • --tc-heuristic-recover={COMMIT|ROLLBACK}

    Property Value
    Command-Line Format --tc-heuristic-recover=name
    Type Enumeration
    Default Value COMMIT
    Valid Values

    COMMIT

    ROLLBACK

    The type of decision to use in the heuristic recovery process. To use this option, two or more storage engines that support XA transactions must be installed.

  • --temp-pool

    Property Value
    Command-Line Format --temp-pool
    Type Boolean
    Default Value (Other) FALSE
    Default Value (Linux) TRUE

    This option is ignored except on Linux. On Linux, it causes most temporary files created by the server to use a small set of names, rather than a unique name for each new file. This works around a problem in the Linux kernel dealing with creating many new files with different names. With the old behavior, Linux seems to leak memory, because it is being allocated to the directory entry cache rather than to the disk cache.

  • --transaction-isolation=level

    Property Value
    Command-Line Format --transaction-isolation=name
    Type Enumeration
    Default Value REPEATABLE-READ
    Valid Values

    READ-UNCOMMITTED

    READ-COMMITTED

    REPEATABLE-READ

    SERIALIZABLE

    Sets the default transaction isolation level. The level value can be READ-UNCOMMITTED, READ-COMMITTED, REPEATABLE-READ, or SERIALIZABLE. See Section 13.3.6, “SET TRANSACTION Syntax”.

    The default transaction isolation level can also be set at runtime using the SET TRANSACTION statement or by setting the tx_isolation system variable.

  • --transaction-read-only

    Property Value
    Command-Line Format --transaction-read-only
    Introduced 5.6.5
    Type Boolean
    Default Value OFF

    Sets the default transaction access mode. By default, read-only mode is disabled, so the mode is read/write.

    To set the default transaction access mode at runtime, use the SET TRANSACTION statement or set the tx_read_only system variable. See Section 13.3.6, “SET TRANSACTION Syntax”.

  • --tmpdir=dir_name, -t dir_name

    Property Value
    Command-Line Format --tmpdir=dir_name
    System Variable tmpdir
    Scope Global
    Dynamic No
    Type Directory name

    The path of the directory to use for creating temporary files. It might be useful if your default /tmp directory resides on a partition that is too small to hold temporary tables. This option accepts several paths that are used in round-robin fashion. Paths should be separated by colon characters (:) on Unix and semicolon characters (;) on Windows. If the MySQL server is acting as a replication slave, you should not set --tmpdir to point to a directory on a memory-based file system or to a directory that is cleared when the server host restarts. For more information about the storage location of temporary files, see Section B.5.3.5, “Where MySQL Stores Temporary Files”. A replication slave needs some of its temporary files to survive a machine restart so that it can replicate temporary tables or LOAD DATA INFILE operations. If files in the temporary file directory are lost when the server restarts, replication fails.

  • --user={user_name|user_id}, -u {user_name|user_id}

    Property Value
    Command-Line Format --user=name
    Type String

    Run the mysqld server as the user having the name user_name or the numeric user ID user_id. (User in this context refers to a system login account, not a MySQL user listed in the grant tables.)

    This option is mandatory when starting mysqld as root. The server changes its user ID during its startup sequence, causing it to run as that particular user rather than as root. See Section 6.1.1, “Security Guidelines”.

    To avoid a possible security hole where a user adds a --user=root option to a my.cnf file (thus causing the server to run as root), mysqld uses only the first --user option specified and produces a warning if there are multiple --user options. Options in /etc/my.cnf and $MYSQL_HOME/my.cnf are processed before command-line options, so it is recommended that you put a --user option in /etc/my.cnf and specify a value other than root. The option in /etc/my.cnf is found before any other --user options, which ensures that the server runs as a user other than root, and that a warning results if any other --user option is found.

  • --verbose, -v

    Use this option with the --help option for detailed help.

  • --version, -V

    Display version information and exit.

5.1.7 Server System Variables

The MySQL server maintains many system variables that configure its operation. Each system variable has a default value. System variables can be set at server startup using options on the command line or in an option file. Most of them can be changed dynamically at runtime using the SET statement, which enables you to modify operation of the server without having to stop and restart it. You can also use system variable values in expressions.

At runtime, setting a global system variable value requires the SUPER privilege. Setting a session system variable value normally requires no special privileges and can be done by any user, although there are exceptions. For more information, see Section 5.1.8.1, “System Variable Privileges”

There are several ways to see the names and values of system variables:

  • To see the values that a server will use based on its compiled-in defaults and any option files that it reads, use this command:

    mysqld --verbose --help
    
  • To see the values that a server will use based only on its compiled-in defaults, ignoring the settings in any option files, use this command:

    mysqld --no-defaults --verbose --help
    
  • To see the current values used by a running server, use the SHOW VARIABLES statement.

This section provides a description of each system variable. For a system variable summary table, see Section 5.1.4, “Server System Variable Reference”. For more information about manipulation of system variables, see Section 5.1.8, “Using System Variables”.

For additional system variable information, see these sections:

Note

Some of the following variable descriptions refer to enabling or disabling a variable. These variables can be enabled with the SET statement by setting them to ON or 1, or disabled by setting them to OFF or 0. Boolean variables can be set at startup to the values ON, TRUE, OFF, and FALSE (not case sensitive), as well as 1 and 0. See Section 4.2.5, “Program Option Modifiers”.

Some system variables control the size of buffers or caches. For a given buffer, the server might need to allocate internal data structures. These structures typically are allocated from the total memory allocated to the buffer, and the amount of space required might be platform dependent. This means that when you assign a value to a system variable that controls a buffer size, the amount of space actually available might differ from the value assigned. In some cases, the amount might be less than the value assigned. It is also possible that the server will adjust a value upward. For example, if you assign a value of 0 to a variable for which the minimal value is 1024, the server will set the value to 1024.

Values for buffer sizes, lengths, and stack sizes are given in bytes unless otherwise specified.

Some system variables take file name values. Unless otherwise specified, the default file location is the data directory if the value is a relative path name. To specify the location explicitly, use an absolute path name. Suppose that the data directory is /var/mysql/data. If a file-valued variable is given as a relative path name, it will be located under /var/mysql/data. If the value is an absolute path name, its location is as given by the path name.

  • authentication_windows_log_level

    Property Value
    Command-Line Format --authentication-windows-log-level
    Introduced 5.6.10
    System Variable authentication_windows_log_level
    Scope Global
    Dynamic No
    Type Integer
    Default Value 2
    Minimum Value 0
    Maximum Value 4

    This variable is available only if the authentication_windows Windows authentication plugin is enabled and debugging code is enabled. See Section 6.5.1.7, “Windows Pluggable Authentication”.

    This variable sets the logging level for the Windows authentication plugin. The following table shows the permitted values.

    Value Description
    0 No logging
    1 Log only error messages
    2 Log level 1 messages and warning messages
    3 Log level 2 messages and information notes
    4 Log level 3 messages and debug messages
  • authentication_windows_use_principal_name

    Property Value
    Command-Line Format --authentication-windows-use-principal-name
    Introduced 5.6.10
    System Variable authentication_windows_use_principal_name
    Scope Global
    Dynamic No
    Type Boolean
    Default Value ON

    This variable is available only if the authentication_windows Windows authentication plugin is enabled. See Section 6.5.1.7, “Windows Pluggable Authentication”.

    A client that authenticates using the InitSecurityContext() function should provide a string identifying the service to which it connects (targetName). MySQL uses the principal name (UPN) of the account under which the server is running. The UPN has the form user_id@computer_name and need not be registered anywhere to be used. This UPN is sent by the server at the beginning of authentication handshake.

    This variable controls whether the server sends the UPN in the initial challenge. By default, the variable is enabled. For security reasons, it can be disabled to avoid sending the server's account name to a client in clear text. If the variable is disabled, the server always sends a 0x00 byte in the first challenge, the client does not specify targetName, and as a result, NTLM authentication is used.

    If the server fails to obtain its UPN (which will happen primarily in environments that do not support Kerberos authentication), the UPN is not sent by the server and NTLM authentication is used.

  • autocommit

    Property Value
    Command-Line Format --autocommit[=#]
    System Variable autocommit
    Scope Global, Session
    Dynamic Yes
    Type Boolean
    Default Value ON

    The autocommit mode. If set to 1, all changes to a table take effect immediately. If set to 0, you must use COMMIT to accept a transaction or ROLLBACK to cancel it. If autocommit is 0 and you change it to 1, MySQL performs an automatic COMMIT of any open transaction. Another way to begin a transaction is to use a START TRANSACTION or BEGIN statement. See Section 13.3.1, “START TRANSACTION, COMMIT, and ROLLBACK Syntax”.

    By default, client connections begin with autocommit set to 1. To cause clients to begin with a default of 0, set the global autocommit value by starting the server with the --autocommit=0 option. To set the variable using an option file, include these lines:

    [mysqld]
    autocommit=0
    
  • automatic_sp_privileges

    Property Value
    System Variable automatic_sp_privileges
    Scope Global
    Dynamic Yes
    Type Boolean
    Default Value TRUE

    When this variable has a value of 1 (the default), the server automatically grants the EXECUTE and ALTER ROUTINE privileges to the creator of a stored routine, if the user cannot already execute and alter or drop the routine. (The ALTER ROUTINE privilege is required to drop the routine.) The server also automatically drops those privileges from the creator when the routine is dropped. If automatic_sp_privileges is 0, the server does not automatically add or drop these privileges.

    The creator of a routine is the account used to execute the CREATE statement for it. This might not be the same as the account named as the DEFINER in the routine definition.

    See also Section 20.2.2, “Stored Routines and MySQL Privileges”.

  • avoid_temporal_upgrade

    Property Value
    Command-Line Format --avoid-temporal-upgrade={OFF|ON}
    Introduced 5.6.24
    Deprecated 5.6.24
    System Variable avoid_temporal_upgrade
    Scope Global
    Dynamic Yes
    Type Boolean
    Default Value OFF

    This variable controls whether ALTER TABLE implicitly upgrades temporal columns found to be in pre-5.6.4 format (TIME, DATETIME, and TIMESTAMP columns without support for fractional seconds precision). Upgrading such columns requires a table rebuild, which prevents any use of fast alterations that might otherwise apply to the operation to be performed.

    This variable is disabled by default. Enabling it causes ALTER TABLE not to rebuild temporal columns and thereby be able to take advantage of possible fast alterations.

    This variable was added in MySQL 5.6.24. It is deprecated and will be removed in a future MySQL release.

  • back_log

    Property Value
    System Variable back_log
    Scope Global
    Dynamic No
    Type Integer
    Default Value (>= 5.6.6) -1 (signifies autosizing; do not assign this literal value)
    Default Value (<= 5.6.5) 50
    Minimum Value 1
    Maximum Value 65535

    The number of outstanding connection requests MySQL can have. This comes into play when the main MySQL thread gets very many connection requests in a very short time. It then takes some time (although very little) for the main thread to check the connection and start a new thread. The back_log value indicates how many requests can be stacked during this short time before MySQL momentarily stops answering new requests. You need to increase this only if you expect a large number of connections in a short period of time.

    In other words, this value is the size of the listen queue for incoming TCP/IP connections. Your operating system has its own limit on the size of this queue. The manual page for the Unix listen() system call should have more details. Check your OS documentation for the maximum value for this variable. back_log cannot be set higher than your operating system limit.

    The default value is based on the following formula, capped to a limit of 900:

    50 + (max_connections / 5)
    
  • basedir

    Property Value
    Command-Line Format --basedir=dir_name
    System Variable basedir
    Scope Global
    Dynamic No
    Type Directory name
    Default Value configuration-dependent default

    The path to the MySQL installation base directory.

  • big_tables

    Property Value
    Command-Line Format --big-tables
    System Variable big_tables
    Scope Global, Session
    Dynamic Yes
    Type Boolean
    Default Value OFF

    If set to 1, all temporary tables are stored on disk rather than in memory. This is a little slower, but the error The table tbl_name is full does not occur for SELECT operations that require a large temporary table. The default value for a new connection is 0 (use in-memory temporary tables). Normally, you should never need to set this variable, because in-memory tables are automatically converted to disk-based tables as required.

  • bind_address

    Property Value
    Command-Line Format --bind-address=addr
    System Variable (>= 5.6.1) bind_address
    Scope (>= 5.6.1) Global
    Dynamic (>= 5.6.1) No
    Type String
    Default Value (>= 5.6.6) *
    Default Value (<= 5.6.5) 0.0.0.0

    The value of the --bind-address option.

  • block_encryption_mode

    Property Value
    Command-Line Format --block-encryption-mode=#
    Introduced 5.6.17
    System Variable block_encryption_mode
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value aes-128-ecb

    This variable controls the block encryption mode for block-based algorithms such as AES. It affects encryption for AES_ENCRYPT() and AES_DECRYPT().

    block_encryption_mode takes a value in aes-keylen-mode format, where keylen is the key length in bits and mode is the encryption mode. The value is not case-sensitive. Permitted keylen values are 128, 192, and 256. Permitted encryption modes depend on whether MySQL was compiled using OpenSSL or yaSSL:

    • For OpenSSL, permitted mode values are: ECB, CBC, CFB1, CFB8, CFB128, OFB

    • For yaSSL, permitted mode values are: ECB, CBC

    For example, this statement causes the AES encryption functions to use a key length of 256 bits and the CBC mode:

    SET block_encryption_mode = 'aes-256-cbc';
    

    An error occurs for attempts to set block_encryption_mode to a value containing an unsupported key length or a mode that the SSL library does not support.

    This variable was added in MySQL 5.6.17.

  • bulk_insert_buffer_size

    Property Value
    Command-Line Format --bulk-insert-buffer-size=#
    System Variable bulk_insert_buffer_size
    Scope Global, Session
    Dynamic Yes
    Type Integer
    Default Value 8388608
    Minimum Value 0
    Maximum Value (64-bit platforms) 18446744073709551615
    Maximum Value (32-bit platforms) 4294967295

    MyISAM uses a special tree-like cache to make bulk inserts faster for INSERT ... SELECT, INSERT ... VALUES (...), (...), ..., and LOAD DATA INFILE when adding data to nonempty tables. This variable limits the size of the cache tree in bytes per thread. Setting it to 0 disables this optimization. The default value is 8MB.

  • character_set_client

    Property Value
    System Variable character_set_client
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value utf8

    The character set for statements that arrive from the client. The session value of this variable is set using the character set requested by the client when the client connects to the server. (Many clients support a --default-character-set option to enable this character set to be specified explicitly. See also Section 10.4, “Connection Character Sets and Collations”.) The global value of the variable is used to set the session value in cases when the client-requested value is unknown or not available, or the server is configured to ignore client requests:

    • The client requests a character set not known to the server. For example, a Japanese-enabled client requests sjis when connecting to a server not configured with sjis support.

    • The client is from a version of MySQL older than MySQL 4.1, and thus does not request a character set.

    • mysqld was started with the --skip-character-set-client-handshake option, which causes it to ignore client character set configuration. This reproduces MySQL 4.0 behavior and is useful should you wish to upgrade the server without upgrading all the clients.

    Some character sets cannot be used as the client character set. Attempting to use them as the character_set_client value produces an error. See Impermissible Client Character Sets.

  • character_set_connection

    Property Value
    System Variable character_set_connection
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value utf8

    The character set used for literals specified without a character set introducer and for number-to-string conversion. For information about introducers, see Section 10.3.8, “Character Set Introducers”.

  • character_set_database

    Property Value
    System Variable character_set_database
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value latin1
    Footnote This option is dynamic, but only the server should set this information. You should not set the value of this variable manually.

    The character set used by the default database. The server sets this variable whenever the default database changes. If there is no default database, the variable has the same value as character_set_server.

  • character_set_filesystem

    Property Value
    Command-Line Format --character-set-filesystem=name
    System Variable character_set_filesystem
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value binary

    The file system character set. This variable is used to interpret string literals that refer to file names, such as in the LOAD DATA INFILE and SELECT ... INTO OUTFILE statements and the LOAD_FILE() function. Such file names are converted from character_set_client to character_set_filesystem before the file opening attempt occurs. The default value is binary, which means that no conversion occurs. For systems on which multibyte file names are permitted, a different value may be more appropriate. For example, if the system represents file names using UTF-8, set character_set_filesystem to 'utf8mb4'.

  • character_set_results

    Property Value
    System Variable character_set_results
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value utf8

    The character set used for returning query results to the client. This includes result data such as column values, result metadata such as column names, and error messages.

  • character_set_server

    Property Value
    Command-Line Format --character-set-server
    System Variable character_set_server
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value latin1

    The server's default character set.

  • character_set_system

    Property Value
    System Variable character_set_system
    Scope Global
    Dynamic No
    Type String
    Default Value utf8

    The character set used by the server for storing identifiers. The value is always utf8.

  • character_sets_dir

    Property Value
    Command-Line Format --character-sets-dir=dir_name
    System Variable character_sets_dir
    Scope Global
    Dynamic No
    Type Directory name

    The directory where character sets are installed.

  • collation_connection

    Property Value
    System Variable collation_connection
    Scope Global, Session
    Dynamic Yes
    Type String

    The collation of the connection character set. collation_connection is important for comparisons of literal strings. For comparisons of strings with column values, collation_connection does not matter because columns have their own collation, which has a higher collation precedence (see Section 10.8.4, “Collation Coercibility in Expressions”).

  • collation_database

    Property Value
    System Variable collation_database
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value latin1_swedish_ci
    Footnote This option is dynamic, but only the server should set this information. You should not set the value of this variable manually.

    The collation used by the default database. The server sets this variable whenever the default database changes. If there is no default database, the variable has the same value as collation_server.

  • collation_server

    Property Value
    Command-Line Format --collation-server
    System Variable collation_server
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value latin1_swedish_ci

    The server's default collation.

  • completion_type

    Property Value
    Command-Line Format --completion-type=#
    System Variable completion_type
    Scope Global, Session
    Dynamic Yes
    Type Enumeration
    Default Value NO_CHAIN
    Valid Values

    NO_CHAIN

    CHAIN

    RELEASE

    0

    1

    2

    The transaction completion type. This variable can take the values shown in the following table. The variable can be assigned using either the name values or corresponding integer values.

    Value Description
    NO_CHAIN (or 0) COMMIT and ROLLBACK are unaffected. This is the default value.
    CHAIN (or 1) COMMIT and ROLLBACK are equivalent to COMMIT AND CHAIN and ROLLBACK AND CHAIN, respectively. (A new transaction starts immediately with the same isolation level as the just-terminated transaction.)
    RELEASE (or 2) COMMIT and ROLLBACK are equivalent to COMMIT RELEASE and ROLLBACK RELEASE, respectively. (The server disconnects after terminating the transaction.)

    completion_type affects transactions that begin with START TRANSACTION or BEGIN and end with COMMIT or ROLLBACK. It does not apply to implicit commits resulting from execution of the statements listed in Section 13.3.3, “Statements That Cause an Implicit Commit”. It also does not apply for XA COMMIT, XA ROLLBACK, or when autocommit=1.

  • concurrent_insert

    Property Value
    Command-Line Format --concurrent-insert[=#]
    System Variable concurrent_insert
    Scope Global
    Dynamic Yes
    Type Enumeration
    Default Value AUTO
    Valid Values

    NEVER

    AUTO

    ALWAYS

    0

    1

    2

    If AUTO (the default), MySQL permits INSERT and SELECT statements to run concurrently for MyISAM tables that have no free blocks in the middle of the data file. If you start mysqld with --skip-new, this variable is set to NEVER.

    This variable can take the values shown in the following table. The variable can be assigned using either the name values or corresponding integer values.

    Value Description
    NEVER (or 0) Disables concurrent inserts
    AUTO (or 1) (Default) Enables concurrent insert for MyISAM tables that do not have holes
    ALWAYS (or 2) Enables concurrent inserts for all MyISAM tables, even those that have holes. For a table with a hole, new rows are inserted at the end of the table if it is in use by another thread. Otherwise, MySQL acquires a normal write lock and inserts the row into the hole.

    See also Section 8.11.3, “Concurrent Inserts”.

  • connect_timeout

    Property Value
    Command-Line Format --connect-timeout=#
    System Variable connect_timeout
    Scope Global
    Dynamic Yes
    Type Integer
    Default Value 10
    Minimum Value 2
    Maximum Value 31536000

    The number of seconds that the mysqld server waits for a connect packet before responding with Bad handshake. The default value is 10 seconds.

    Increasing the connect_timeout value might help if clients frequently encounter errors of the form Lost connection to MySQL server at 'XXX', system error: errno.

  • core_file

    Property Value
    Introduced 5.6.2
    System Variable core_file
    Scope Global
    Dynamic No
    Type Boolean
    Default Value OFF

    Whether to write a core file if the server crashes. This variable is set by the --core-file option.

  • datadir

    Property Value
    Command-Line Format --datadir=dir_name
    System Variable datadir
    Scope Global
    Dynamic No
    Type Directory name

    The path to the MySQL server data directory. Relative paths are resolved with respect to the current directory. If the server will be started automatically (that is, in contexts for which you cannot assume what the current directory will be), it is best to specify the datadir value as an absolute path.

  • date_format

    This variable is unused. It is deprecated and will be removed in a future MySQL release.

  • datetime_format

    This variable is unused. It is deprecated and will be removed in a future MySQL release.

  • debug

    Property Value
    Command-Line Format --debug[=debug_options]
    System Variable debug
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value (Windows) d:t:i:O,\mysqld.trace
    Default Value (Unix) d:t:i:o,/tmp/mysqld.trace

    This variable indicates the current debugging settings. It is available only for servers built with debugging support. The initial value comes from the value of instances of the --debug option given at server startup. The global and session values may be set at runtime.

    Setting the session value of this system variable is a restricted operation. The session user must have privileges sufficient to set restricted session variables. See Section 5.1.8.1, “System Variable Privileges”.

    Assigning a value that begins with + or - cause the value to added to or subtracted from the current value:

    mysql> SET debug = 'T';
    mysql> SELECT @@debug;
    +---------+
    | @@debug |
    +---------+
    | T       |
    +---------+
    
    mysql> SET debug = '+P';
    mysql> SELECT @@debug;
    +---------+
    | @@debug |
    +---------+
    | P:T     |
    +---------+
    
    mysql> SET debug = '-P';
    mysql> SELECT @@debug;
    +---------+
    | @@debug |
    +---------+
    | T       |
    +---------+
    

    For more information, see Section 24.5.3, “The DBUG Package”.

  • debug_sync

    Property Value
    System Variable debug_sync
    Scope Session
    Dynamic Yes
    Type String

    This variable is the user interface to the Debug Sync facility. Use of Debug Sync requires that MySQL be configured with the -DENABLE_DEBUG_SYNC=1 CMake option (see Section 2.9.4, “MySQL Source-Configuration Options”). If Debug Sync is not compiled in, this system variable is not available.

    The global variable value is read only and indicates whether the facility is enabled. By default, Debug Sync is disabled and the value of debug_sync is OFF. If the server is started with --debug-sync-timeout=N, where N is a timeout value greater than 0, Debug Sync is enabled and the value of debug_sync is ON - current signal followed by the signal name. Also, N becomes the default timeout for individual synchronization points.

    The session value can be read by any user and will have the same value as the global variable. The session value can be set to control synchronization points.

    Setting the session value of this system variable is a restricted operation. The session user must have privileges sufficient to set restricted session variables. See Section 5.1.8.1, “System Variable Privileges”.

    For a description of the Debug Sync facility and how to use synchronization points, see MySQL Internals: Test Synchronization.

  • default_storage_engine

    Property Value
    Command-Line Format --default-storage-engine=name
    System Variable default_storage_engine
    Scope Global, Session
    Dynamic Yes
    Type Enumeration
    Default Value InnoDB

    The default storage engine. This variable sets the storage engine for permanent tables only. To set the storage engine for TEMPORARY tables, set the default_tmp_storage_engine system variable.

    To see which storage engines are available and enabled, use the SHOW ENGINES statement or query the INFORMATION_SCHEMA ENGINES table.

    default_storage_engine should be used in preference to storage_engine, which is deprecated.

    If you disable the default storage engine at server startup, you must set the default engine for both permanent and TEMPORARY tables to a different engine or the server will not start.

  • default_tmp_storage_engine

    Property Value
    Command-Line Format --default-tmp-storage-engine=name
    Introduced 5.6.3
    System Variable default_tmp_storage_engine
    Scope Global, Session
    Dynamic Yes
    Type Enumeration
    Default Value InnoDB

    The default storage engine for TEMPORARY tables (created with CREATE TEMPORARY TABLE). To set the storage engine for permanent tables, set the default_storage_engine system variable.

    If you disable the default storage engine at server startup, you must set the default engine for both permanent and TEMPORARY tables to a different engine or the server will not start.

  • default_week_format

    Property Value
    Command-Line Format --default-week-format=#
    System Variable default_week_format
    Scope Global, Session
    Dynamic Yes
    Type Integer
    Default Value 0
    Minimum Value 0
    Maximum Value 7

    The default mode value to use for the WEEK() function. See Section 12.7, “Date and Time Functions”.

  • delay_key_write

    Property Value
    Command-Line Format --delay-key-write[=name]
    System Variable delay_key_write
    Scope Global
    Dynamic Yes
    Type Enumeration
    Default Value ON
    Valid Values

    ON

    OFF

    ALL

    This option applies only to MyISAM tables. It can have one of the following values to affect handling of the DELAY_KEY_WRITE table option that can be used in CREATE TABLE statements.

    Option Description
    OFF DELAY_KEY_WRITE is ignored.
    ON MySQL honors any DELAY_KEY_WRITE option specified in CREATE TABLE statements. This is the default value.
    ALL All new opened tables are treated as if they were created with the DELAY_KEY_WRITE option enabled.

    If DELAY_KEY_WRITE is enabled for a table, the key buffer is not flushed for the table on every index update, but only when the table is closed. This speeds up writes on keys a lot, but if you use this feature, you should add automatic checking of all MyISAM tables by starting the server with the --myisam-recover-options option (for example, --myisam-recover-options=BACKUP,FORCE). See Section 5.1.6, “Server Command Options”, and Section 15.2.1, “MyISAM Startup Options”.

    Warning

    If you enable external locking with --external-locking, there is no protection against index corruption for tables that use delayed key writes.

  • delayed_insert_limit

    Property Value
    Command-Line Format --delayed-insert-limit=#
    Deprecated 5.6.7
    System Variable delayed_insert_limit
    Scope Global
    Dynamic Yes
    Type Integer
    Default Value 100
    Minimum Value 1
    Maximum Value (64-bit platforms) 18446744073709551615
    Maximum Value (32-bit platforms) 4294967295

    After inserting delayed_insert_limit delayed rows into a nontransactional table, the INSERT DELAYED handler thread checks whether there are any SELECT statements pending. If so, it permits them to execute before continuing to insert delayed rows.

    This system variable is deprecated (because DELAYED inserts are deprecated), and will be removed in a future release.

  • delayed_insert_timeout

    Property Value
    Command-Line Format --delayed-insert-timeout=#
    Deprecated 5.6.7
    System Variable delayed_insert_timeout
    Scope Global
    Dynamic Yes
    Type Integer
    Default Value 300

    How many seconds an INSERT DELAYED handler thread should wait for INSERT statements before terminating.

    This system variable is deprecated (because DELAYED inserts are deprecated), and will be removed in a future release.

  • delayed_queue_size

    Property Value
    Command-Line Format --delayed-queue-size=#
    Deprecated 5.6.7
    System Variable delayed_queue_size
    Scope Global
    Dynamic Yes
    Type Integer
    Default Value 1000
    Minimum Value 1
    Maximum Value (64-bit platforms) 18446744073709551615
    Maximum Value (32-bit platforms) 4294967295

    This is a per-table limit on the number of rows to queue when handling INSERT DELAYED statements for nontransactional tables. If the queue becomes full, any client that issues an INSERT DELAYED statement waits until there is room in the queue again.

    This system variable is deprecated (because DELAYED inserts are deprecated), and will be removed in a future release.

  • disconnect_on_expired_password

    Property Value
    Command-Line Format --disconnect-on-expired-password[=#]
    Introduced 5.6.10
    System Variable disconnect_on_expired_password
    Scope Global
    Dynamic No
    Type Boolean
    Default Value ON

    This variable controls how the server handles clients with expired passwords:

    For more information about the interaction of client and server settings relating to expired-password handling, see Section 6.3.6, “Password Expiration and Sandbox Mode”.

  • div_precision_increment

    Property Value
    Command-Line Format --div-precision-increment=#
    System Variable div_precision_increment
    Scope Global, Session
    Dynamic Yes
    Type Integer
    Default Value 4
    Minimum Value 0
    Maximum Value 30

    This variable indicates the number of digits by which to increase the scale of the result of division operations performed with the / operator. The default value is 4. The minimum and maximum values are 0 and 30, respectively. The following example illustrates the effect of increasing the default value.

    mysql> SELECT 1/7;
    +--------+
    | 1/7    |
    +--------+
    | 0.1429 |
    +--------+
    mysql> SET div_precision_increment = 12;
    mysql> SELECT 1/7;
    +----------------+
    | 1/7            |
    +----------------+
    | 0.142857142857 |
    +----------------+
    
  • engine_condition_pushdown

    Property Value
    Command-Line Format --engine-condition-pushdown
    Deprecated Yes (removed in 5.6.1); use optimizer_switch
    System Variable engine_condition_pushdown
    Scope Global, Session
    Dynamic Yes
    Type Boolean
    Default Value ON

    This variable was removed in MySQL 5.6.1. Use the engine_condition_pushdown flag of the optimizer_switch variable instead. See Section 8.9.2, “Switchable Optimizations”.

  • end_markers_in_json

    Property Value
    Introduced 5.6.5
    System Variable end_markers_in_json
    Scope Global, Session
    Dynamic Yes
    Type Boolean
    Default Value OFF

    Whether optimizer JSON output should add end markers. See MySQL Internals: The end_markers_in_json System Variable.

  • eq_range_index_dive_limit

    Property Value
    Introduced 5.6.5
    System Variable eq_range_index_dive_limit
    Scope Global, Session
    Dynamic Yes
    Type Integer
    Default Value 10
    Minimum Value 0
    Maximum Value 4294967295

    This variable indicates the number of equality ranges in an equality comparison condition when the optimizer should switch from using index dives to index statistics in estimating the number of qualifying rows. It applies to evaluation of expressions that have either of these equivalent forms, where the optimizer uses a nonunique index to look up col_name values:

    col_name IN(val1, ..., valN)
    col_name = val1 OR ... OR col_name = valN
    

    In both cases, the expression contains N equality ranges. The optimizer can make row estimates using index dives or index statistics. If eq_range_index_dive_limit is greater than 0, the optimizer uses existing index statistics instead of index dives if there are eq_range_index_dive_limit or more equality ranges. Thus, to permit use of index dives for up to N equality ranges, set eq_range_index_dive_limit to N + 1. To disable use of index statistics and always use index dives regardless of N, set eq_range_index_dive_limit to 0.

    For more information, see Equality Range Optimization of Many-Valued Comparisons.

    To update table index statistics for best estimates, use ANALYZE TABLE.

  • error_count

    The number of errors that resulted from the last statement that generated messages. This variable is read only. See Section 13.7.5.18, “SHOW ERRORS Syntax”.

  • event_scheduler

    Property Value
    Command-Line Format --event-scheduler[=value]
    System Variable event_scheduler
    Scope Global
    Dynamic Yes
    Type Enumeration
    Default Value OFF
    Valid Values

    ON

    OFF

    DISABLED

    This variable indicates the status of the Event Scheduler; possible values are ON, OFF, and DISABLED, with the default being OFF. This variable and its effects on the Event Scheduler's operation are discussed in greater detail in the Overview section of the Events chapter.

  • explicit_defaults_for_timestamp

    Property Value
    Command-Line Format --explicit-defaults-for-timestamp=#
    Introduced 5.6.6
    Deprecated 5.6.6
    System Variable explicit_defaults_for_timestamp
    Scope Global, Session
    Dynamic Yes
    Type Boolean
    Default Value OFF

    This system variable determines whether the server enables certain nonstandard behaviors for default values and NULL-value handling in TIMESTAMP columns. By default, explicit_defaults_for_timestamp is disabled, which enables the nonstandard behaviors.

    If explicit_defaults_for_timestamp is disabled, the server enables the nonstandard behaviors and handles TIMESTAMP columns as follows:

    • TIMESTAMP columns not explicitly declared with the NULL attribute are automatically declared with the NOT NULL attribute. Assigning such a column a value of NULL is permitted and sets the column to the current timestamp.

    • The first TIMESTAMP column in a table, if not explicitly declared with the NULL attribute or an explicit DEFAULT or ON UPDATE attribute, is automatically declared with the DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP attributes.

    • TIMESTAMP columns following the first one, if not explicitly declared with the NULL attribute or an explicit DEFAULT attribute, are automatically declared as DEFAULT '0000-00-00 00:00:00' (the zero timestamp). For inserted rows that specify no explicit value for such a column, the column is assigned '0000-00-00 00:00:00' and no warning occurs.

      Depending on whether strict SQL mode or the NO_ZERO_DATE SQL mode is enabled, a default value of '0000-00-00 00:00:00' may be invalid. Be aware that the TRADITIONAL SQL mode includes strict mode and NO_ZERO_DATE. See Section 5.1.10, “Server SQL Modes”.

    As of MySQL 5.6.6, the nonstandard behaviors just described are deprecated and will be removed in a future MySQL release.

    If explicit_defaults_for_timestamp is enabled, the server disables the nonstandard behaviors and handles TIMESTAMP columns as follows:

    • It is not possible to assign a TIMESTAMP column a value of NULL to set it to the current timestamp. To assign the current timestamp, set the column to CURRENT_TIMESTAMP or a synonym such as NOW().

    • TIMESTAMP columns not explicitly declared with the NOT NULL attribute are automatically declared with the NULL attribute and permit NULL values. Assigning such a column a value of NULL sets it to NULL, not the current timestamp.

    • TIMESTAMP columns declared with the NOT NULL attribute do not permit NULL values. For inserts that specify NULL for such a column, the result is either an error for a single-row insert or if strict SQL mode is enabled, or '0000-00-00 00:00:00' is inserted for multiple-row inserts with strict SQL mode disabled. In no case does assigning the column a value of NULL set it to the current timestamp.

    • TIMESTAMP columns explicitly declared with the NOT NULL attribute and without an explicit DEFAULT attribute are treated as having no default value. For inserted rows that specify no explicit value for such a column, the result depends on the SQL mode. If strict SQL mode is enabled, an error occurs. If strict SQL mode is not enabled, the column is declared with the implicit default of '0000-00-00 00:00:00' and a warning occurs. This is similar to how MySQL treats other temporal types such as DATETIME.

    • No TIMESTAMP column is automatically declared with the DEFAULT CURRENT_TIMESTAMP or ON UPDATE CURRENT_TIMESTAMP attributes. Those attributes must be explicitly specified.

    • The first TIMESTAMP column in a table is not handled differently from TIMESTAMP columns following the first one.

    If explicit_defaults_for_timestamp is disabled at server startup, this warning appears in the error log:

    [Warning] TIMESTAMP with implicit DEFAULT value is deprecated.
    Please use --explicit_defaults_for_timestamp server option (see
    documentation for more details).
    

    As indicated by the warning, to disable the deprecated nonstandard behaviors, enable the explicit_defaults_for_timestamp system variable at server startup.

    Note

    explicit_defaults_for_timestamp is itself deprecated because its only purpose is to permit control over deprecated TIMESTAMP behaviors that are to be removed in a future MySQL release. When removal of those behaviors occurs, explicit_defaults_for_timestamp will have no purpose and will be removed as well.

    For additional information, see Section 11.3.5, “Automatic Initialization and Updating for TIMESTAMP and DATETIME”.

  • external_user

    Property Value
    System Variable external_user
    Scope Session
    Dynamic No
    Type String

    The external user name used during the authentication process, as set by the plugin used to authenticate the client. With native (built-in) MySQL authentication, or if the plugin does not set the value, this variable is NULL. See Section 6.3.8, “Proxy Users”.

  • flush

    Property Value
    Command-Line Format --flush
    System Variable flush
    Scope Global
    Dynamic Yes
    Type Boolean
    Default Value OFF

    If ON, the server flushes (synchronizes) all changes to disk after each SQL statement. Normally, MySQL does a write of all changes to disk only after each SQL statement and lets the operating system handle the synchronizing to disk. See Section B.5.3.3, “What to Do If MySQL Keeps Crashing”. This variable is set to ON if you start mysqld with the --flush option.

    Note

    If flush is enabled, the value of flush_time does not matter and changes to flush_time have no effect on flush behavior.

  • flush_time

    Property Value
    Command-Line Format --flush-time=#
    System Variable flush_time
    Scope Global
    Dynamic Yes
    Type Integer
    Default Value (Other, <= 5.6.5) 0
    Default Value (Windows, <= 5.6.5) 1800
    Default Value (>= 5.6.6) 0
    Minimum Value 0

    If this is set to a nonzero value, all tables are closed every flush_time seconds to free up resources and synchronize unflushed data to disk. This option is best used only on systems with minimal resources. The default is 0.

    Note

    If flush is enabled, the value of flush_time does not matter and changes to flush_time have no effect on flush behavior.

  • foreign_key_checks

    Property Value
    System Variable foreign_key_checks
    Scope Global, Session
    Dynamic Yes
    Type Boolean
    Default Value ON

    If set to 1 (the default), foreign key constraints for InnoDB tables are checked. If set to 0, foreign key constraints are ignored, with a couple of exceptions. When re-creating a table that was dropped, an error is returned if the table definition does not conform to the foreign key constraints referencing the table. Likewise, an ALTER TABLE operation returns an error if a foreign key definition is incorrectly formed. For more information, see Section 13.1.17.6, “Using FOREIGN KEY Constraints”.

    Beginning with MySQL NDB Cluster 7.3.2, setting this variable has the same effect on NDB tables as it does for InnoDB tables—previously, the setting was ignored and all such checks were enforced (Bug #14095855). Typically you leave this setting enabled during normal operation, to enforce referential integrity.

    Disabling foreign key checking can be useful for reloading such tables in an order different from that required by their parent/child relationships. See Section 14.6.1.6, “InnoDB and FOREIGN KEY Constraints”.

    Setting foreign_key_checks to 0 also affects data definition statements: DROP SCHEMA drops a schema even if it contains tables that have foreign keys that are referred to by tables outside the schema, and DROP TABLE drops tables that have foreign keys that are referred to by other tables.

    Note

    Setting foreign_key_checks to 1 does not trigger a scan of the existing table data. Therefore, rows added to the table while foreign_key_checks=0 will not be verified for consistency.

    Warning

    With foreign_key_checks=0, dropping an index required by a foreign key constraint places the table in an inconsistent state and causes the foreign key check that occurs at table load to fail. To avoid this problem, remove the foreign key constraint before dropping the index (Bug #70260).

  • ft_boolean_syntax

    Property Value
    Command-Line Format --ft-boolean-syntax=name
    System Variable ft_boolean_syntax
    Scope Global
    Dynamic Yes
    Type String
    Default Value + -><()~*:""&|

    The list of operators supported by boolean full-text searches performed using IN BOOLEAN MODE. See Section 12.9.2, “Boolean Full-Text Searches”.

    The default variable value is '+ -><()~*:""&|'. The rules for changing the value are as follows:

    • Operator function is determined by position within the string.

    • The replacement value must be 14 characters.

    • Each character must be an ASCII nonalphanumeric character.

    • Either the first or second character must be a space.

    • No duplicates are permitted except the phrase quoting operators in positions 11 and 12. These two characters are not required to be the same, but they are the only two that may be.

    • Positions 10, 13, and 14 (which by default are set to :, &, and |) are reserved for future extensions.

  • ft_max_word_len

    Property Value
    Command-Line Format --ft-max-word-len=#
    System Variable ft_max_word_len
    Scope Global
    Dynamic No
    Type Integer
    Minimum Value 10

    The maximum length of the word to be included in a MyISAM FULLTEXT index.

    Note

    FULLTEXT indexes on MyISAM tables must be rebuilt after changing this variable. Use REPAIR TABLE tbl_name QUICK.

  • ft_min_word_len

    Property Value
    Command-Line Format --ft-min-word-len=#
    System Variable ft_min_word_len
    Scope Global
    Dynamic No
    Type Integer
    Default Value 4
    Minimum Value 1

    The minimum length of the word to be included in a MyISAM FULLTEXT index.

    Note

    FULLTEXT indexes on MyISAM tables must be rebuilt after changing this variable. Use REPAIR TABLE tbl_name QUICK.

  • ft_query_expansion_limit

    Property Value
    Command-Line Format --ft-query-expansion-limit=#
    System Variable ft_query_expansion_limit
    Scope Global
    Dynamic No
    Type Integer
    Default Value 20
    Minimum Value 0
    Maximum Value 1000

    The number of top matches to use for full-text searches performed using WITH QUERY EXPANSION.

  • ft_stopword_file

    Property Value
    Command-Line Format --ft-stopword-file=file_name
    System Variable ft_stopword_file
    Scope Global
    Dynamic No
    Type File name

    The file from which to read the list of stopwords for full-text searches on MyISAM tables. The server looks for the file in the data directory unless an absolute path name is given to specify a different directory. All the words from the file are used; comments are not honored. By default, a built-in list of stopwords is used (as defined in the storage/myisam/ft_static.c file). Setting this variable to the empty string ('') disables stopword filtering. See also Section 12.9.4, “Full-Text Stopwords”.

    Note

    FULLTEXT indexes on MyISAM tables must be rebuilt after changing this variable or the contents of the stopword file. Use REPAIR TABLE tbl_name QUICK.

  • general_log

    Property Value
    Command-Line Format --general-log
    System Variable general_log
    Scope Global
    Dynamic Yes
    Type Boolean
    Default Value OFF

    Whether the general query log is enabled. The value can be 0 (or OFF) to disable the log or 1 (or ON) to enable the log. The default value depends on whether the --general_log option is given. The destination for log output is controlled by the log_output system variable; if that value is NONE, no log entries are written even if the log is enabled.

  • general_log_file

    Property Value
    Command-Line Format --general-log-file=file_name
    System Variable general_log_file
    Scope Global
    Dynamic Yes
    Type File name
    Default Value host_name.log

    The name of the general query log file. The default value is host_name.log, but the initial value can be changed with the --general_log_file option.

  • group_concat_max_len

    Property Value
    Command-Line Format --group-concat-max-len=#
    System Variable group_concat_max_len
    Scope Global, Session
    Dynamic Yes
    Type Integer
    Default Value 1024
    Minimum Value 4
    Maximum Value (64-bit platforms) 18446744073709551615
    Maximum Value (32-bit platforms) 4294967295

    The maximum permitted result length in bytes for the GROUP_CONCAT() function. The default is 1024.

  • have_compress

    YES if the zlib compression library is available to the server, NO if not. If not, the COMPRESS() and UNCOMPRESS() functions cannot be used.

  • have_crypt

    YES if the crypt() system call is available to the server, NO if not. If not, the ENCRYPT() function cannot be used.

  • have_csv

    YES if mysqld supports CSV tables, NO if not.

    This variable was removed in MySQL 5.6.1. Use SHOW ENGINES instead.

  • have_dynamic_loading

    YES if mysqld supports dynamic loading of plugins, NO if not. If the value is NO, you cannot use options such as --plugin-load to load plugins at server startup, or the INSTALL PLUGIN statement to load plugins at runtime.

  • have_geometry

    YES if the server supports spatial data types, NO if not.

  • have_innodb

    YES if mysqld supports InnoDB tables. DISABLED if --skip-innodb is used.

    This variable was removed in MySQL 5.6.1. Use SHOW ENGINES instead.

  • have_openssl

    This variable is an alias for have_ssl.

  • have_partitioning

    YES if mysqld supports partitioning.

    This variable was removed in MySQL 5.6.1. Use SHOW PLUGINS instead. For more information, see Chapter 19, Partitioning.

  • have_profiling

    YES if statement profiling capability is present, NO if not. If present, the profiling system variable controls whether this capability is enabled or disabled. See Section 13.7.5.32, “SHOW PROFILES Syntax”.

    This variable is deprecated and will be removed in a future MySQL release.

  • have_query_cache

    YES if mysqld supports the query cache, NO if not.

  • have_rtree_keys

    YES if RTREE indexes are available, NO if not. (These are used for spatial indexes in MyISAM tables.)

  • have_ssl

    YES if mysqld supports SSL connections, NO if not. DISABLED indicates that the server was compiled with SSL support, but was not started with the appropriate --ssl-xxx options. For more information, see Section 6.4.5, “Building MySQL with Support for Encrypted Connections”.

  • have_symlink

    YES if symbolic link support is enabled, NO if not. This is required on Unix for support of the DATA DIRECTORY and INDEX DIRECTORY table options, and on Windows for support of data directory symlinks. If the server is started with the --skip-symbolic-links option, the value is DISABLED.

  • host_cache_size

    Property Value
    Introduced 5.6.5
    System Variable host_cache_size
    Scope Global
    Dynamic Yes
    Type Integer
    Default Value (>= 5.6.8) -1 (signifies autosizing; do not assign this literal value)
    Default Value (<= 5.6.7) 128
    Minimum Value 0
    Maximum Value 65536

    This variable controls the size of the host cache, as well as the size of the Performance Schema host_cache table that exposes the cache contents. Setting the size to 0 disables the host cache. Changing the cache size at runtime causes an implicit FLUSH HOSTS operation that clears the host cache, truncates the host_cache table, and unblocks any blocked hosts.

    The default value is autosized to 128, plus 1 for a value of max_connections up to 500, plus 1 for every increment of 20 over 500 in the max_connections value, capped to a limit of 2000.

    Using the --skip-host-cache option is similar to setting the host_cache_size system variable to 0, but host_cache_size is more flexible because it can also be used to resize, enable, and disable the host cache at runtime, not just at server startup. Starting the server with --skip-host-cache does not prevent changes to the value of host_cache_size, but such changes have no effect and the cache is not re-enabled even if host_cache_size is set larger than 0 at runtime.

    For more information about how the host cache works, see Section 8.12.5.2, “DNS Lookup Optimization and the Host Cache”.

  • hostname

    Property Value
    System Variable hostname
    Scope Global
    Dynamic No
    Type String

    The server sets this variable to the server host name at startup.

  • identity

    This variable is a synonym for the last_insert_id variable. It exists for compatibility with other database systems. You can read its value with SELECT @@identity, and set it using SET identity.

  • ignore_db_dirs

    Property Value
    Introduced 5.6.3
    System Variable ignore_db_dirs
    Scope Global
    Dynamic No
    Type String

    A comma-separated list of names that are not considered as database directories in the data directory. The value is set from any instances of --ignore-db-dir given at server startup.

  • init_connect

    Property Value
    Command-Line Format --init-connect=name
    System Variable init_connect
    Scope Global
    Dynamic Yes
    Type String

    A string to be executed by the server for each client that connects. The string consists of one or more SQL statements, separated by semicolon characters.

    For users that have the SUPER privilege, the content of init_connect is not executed. This is done so that an erroneous value for init_connect does not prevent all clients from connecting. For example, the value might contain a statement that has a syntax error, thus causing client connections to fail. Not executing init_connect for users that have the SUPER privilege enables them to open a connection and fix the init_connect value.

    The server discards any result sets produced by statements in the value of of init_connect.

  • init_file

    Property Value
    Command-Line Format --init-file=file_name
    System Variable init_file
    Scope Global
    Dynamic No
    Type File name

    The name of the file specified with the --init-file option when you start the server. This should be a file containing SQL statements that you want the server to execute when it starts. Each statement must be on a single line and should not include comments. For more information, see the description of --init-file.

  • innodb_xxx

    InnoDB system variables are listed in Section 14.14, “InnoDB Startup Options and System Variables”. These variables control many aspects of storage, memory use, and I/O patterns for InnoDB tables, and are especially important now that InnoDB is the default storage engine.

  • insert_id

    The value to be used by the following INSERT or ALTER TABLE statement when inserting an AUTO_INCREMENT value. This is mainly used with the binary log.

  • interactive_timeout

    Property Value
    Command-Line Format --interactive-timeout=#
    System Variable interactive_timeout
    Scope Global, Session
    Dynamic Yes
    Type Integer
    Default Value 28800
    Minimum Value 1

    The number of seconds the server waits for activity on an interactive connection before closing it. An interactive client is defined as a client that uses the CLIENT_INTERACTIVE option to mysql_real_connect(). See also wait_timeout.

  • join_buffer_size

    Property Value
    Command-Line Format --join-buffer-size=#
    System Variable join_buffer_size
    Scope Global, Session
    Dynamic Yes
    Type Integer
    Default Value (Other, 64-bit platforms, >= 5.6.6) 262144
    Default Value (Other, 64-bit platforms, <= 5.6.5) 131072
    Default Value (Other, 32-bit platforms, >= 5.6.6) 262144
    Default Value (Other, 32-bit platforms, <= 5.6.5) 131072
    Default Value (Windows, >= 5.6.6) 262144
    Default Value (Windows, <= 5.6.5) 131072
    Minimum Value 128
    Maximum Value (Other, 64-bit platforms) 18446744073709547520
    Maximum Value (Other, 32-bit platforms) 4294967295
    Maximum Value (Windows) 4294967295

    The minimum size of the buffer that is used for plain index scans, range index scans, and joins that do not use indexes and thus perform full table scans. Normally, the best way to get fast joins is to add indexes. Increase the value of join_buffer_size to get a faster full join when adding indexes is not possible. One join buffer is allocated for each full join between two tables. For a complex join between several tables for which indexes are not used, multiple join buffers might be necessary.

    Unless Batched Key Access (BKA) is used, there is no gain from setting the buffer larger than required to hold each matching row, and all joins allocate at least the minimum size, so use caution in setting this variable to a large value globally. It is better to keep the global setting small and change to a larger setting only in sessions that are doing large joins. Memory allocation time can cause substantial performance drops if the global size is larger than needed by most queries that use it.

    When BKA is used, the value of join_buffer_size defines how large the batch of keys is in each request to the storage engine. The larger the buffer, the more sequential access will be to the right hand table of a join operation, which can significantly improve performance.

    The default is 256KB. The maximum permissible setting for join_buffer_size is 4GB−1. Larger values are permitted for 64-bit platforms (except 64-bit Windows, for which large values are truncated to 4GB−1 with a warning).

    For additional information about join buffering, see Section 8.2.1.6, “Nested-Loop Join Algorithms”. For information about Batched Key Access, see Section 8.2.1.11, “Block Nested-Loop and Batched Key Access Joins”.

  • keep_files_on_create

    Property Value
    Command-Line Format --keep-files-on-create=#
    System Variable keep_files_on_create
    Scope Global, Session
    Dynamic Yes
    Type Boolean
    Default Value OFF

    If a MyISAM table is created with no DATA DIRECTORY option, the .MYD file is created in the database directory. By default, if MyISAM finds an existing .MYD file in this case, it overwrites it. The same applies to .MYI files for tables created with no INDEX DIRECTORY option. To suppress this behavior, set the keep_files_on_create variable to ON (1), in which case MyISAM will not overwrite existing files and returns an error instead. The default value is OFF (0).

    If a MyISAM table is created with a DATA DIRECTORY or INDEX DIRECTORY option and an existing .MYD or .MYI file is found, MyISAM always returns an error. It will not overwrite a file in the specified directory.

  • key_buffer_size

    Property Value
    Command-Line Format --key-buffer-size=#
    System Variable key_buffer_size
    Scope Global
    Dynamic Yes
    Type Integer
    Default Value 8388608
    Minimum Value 8
    Maximum Value (64-bit platforms) OS_PER_PROCESS_LIMIT
    Maximum Value (32-bit platforms) 4294967295

    Index blocks for MyISAM tables are buffered and are shared by all threads. key_buffer_size is the size of the buffer used for index blocks. The key buffer is also known as the key cache.

    The maximum permissible setting for key_buffer_size is 4GB−1 on 32-bit platforms. Larger values are permitted for 64-bit platforms. The effective maximum size might be less, depending on your available physical RAM and per-process RAM limits imposed by your operating system or hardware platform. The value of this variable indicates the amount of memory requested. Internally, the server allocates as much memory as possible up to this amount, but the actual allocation might be less.

    You can increase the value to get better index handling for all reads and multiple writes; on a system whose primary function is to run MySQL using the MyISAM storage engine, 25% of the machine's total memory is an acceptable value for this variable. However, you should be aware that, if you make the value too large (for example, more than 50% of the machine's total memory), your system might start to page and become extremely slow. This is because MySQL relies on the operating system to perform file system caching for data reads, so you must leave some room for the file system cache. You should also consider the memory requirements of any other storage engines that you may be using in addition to MyISAM.

    For even more speed when writing many rows at the same time, use LOCK TABLES. See Section 8.2.4.1, “Optimizing INSERT Statements”.

    You can check the performance of the key buffer by issuing a SHOW STATUS statement and examining the Key_read_requests, Key_reads, Key_write_requests, and Key_writes status variables. (See Section 13.7.5, “SHOW Syntax”.) The Key_reads/Key_read_requests ratio should normally be less than 0.01. The Key_writes/Key_write_requests ratio is usually near 1 if you are using mostly updates and deletes, but might be much smaller if you tend to do updates that affect many rows at the same time or if you are using the DELAY_KEY_WRITE table option.

    The fraction of the key buffer in use can be determined using key_buffer_size in conjunction with the Key_blocks_unused status variable and the buffer block size, which is available from the key_cache_block_size system variable:

    1 - ((Key_blocks_unused * key_cache_block_size) / key_buffer_size)
    

    This value is an approximation because some space in the key buffer is allocated internally for administrative structures. Factors that influence the amount of overhead for these structures include block size and pointer size. As block size increases, the percentage of the key buffer lost to overhead tends to decrease. Larger blocks results in a smaller number of read operations (because more keys are obtained per read), but conversely an increase in reads of keys that are not examined (if not all keys in a block are relevant to a query).

    It is possible to create multiple MyISAM key caches. The size limit of 4GB applies to each cache individually, not as a group. See Section 8.10.2, “The MyISAM Key Cache”.

  • key_cache_age_threshold

    Property Value
    Command-Line Format --key-cache-age-threshold=#
    System Variable key_cache_age_threshold
    Scope Global
    Dynamic Yes
    Type Integer
    Default Value 300
    Minimum Value 100
    Maximum Value (64-bit platforms) 18446744073709551615
    Maximum Value (32-bit platforms) 4294967295

    This value controls the demotion of buffers from the hot sublist of a key cache to the warm sublist. Lower values cause demotion to happen more quickly. The minimum value is 100. The default value is 300. See Section 8.10.2, “The MyISAM Key Cache”.

  • key_cache_block_size

    Property Value
    Command-Line Format --key-cache-block-size=#
    System Variable key_cache_block_size
    Scope Global
    Dynamic Yes
    Type Integer
    Default Value 1024
    Minimum Value 512
    Maximum Value 16384

    The size in bytes of blocks in the key cache. The default value is 1024. See Section 8.10.2, “The MyISAM Key Cache”.

  • key_cache_division_limit

    Property Value
    Command-Line Format --key-cache-division-limit=#
    System Variable key_cache_division_limit
    Scope Global
    Dynamic Yes
    Type Integer
    Default Value 100
    Minimum Value 1
    Maximum Value 100

    The division point between the hot and warm sublists of the key cache buffer list. The value is the percentage of the buffer list to use for the warm sublist. Permissible values range from 1 to 100. The default value is 100. See Section 8.10.2, “The MyISAM Key Cache”.

  • large_files_support

    Property Value
    System Variable large_files_support
    Scope Global
    Dynamic No

    Whether mysqld was compiled with options for large file support.

  • large_pages

    Property Value
    Command-Line Format --large-pages
    System Variable large_pages
    Scope Global
    Dynamic No
    Platform Specific Linux
    Type Boolean
    Default Value FALSE

    Whether large page support is enabled (via the --large-pages option). See Section 8.12.4.2, “Enabling Large Page Support”.

  • large_page_size

    Property Value
    System Variable large_page_size
    Scope Global
    Dynamic No
    Type Integer
    Default Value 0

    If large page support is enabled, this shows the size of memory pages. Large memory pages are supported only on Linux; on other platforms, the value of this variable is always 0. See Section 8.12.4.2, “Enabling Large Page Support”.

  • last_insert_id

    The value to be returned from LAST_INSERT_ID(). This is stored in the binary log when you use LAST_INSERT_ID() in a statement that updates a table. Setting this variable does not update the value returned by the mysql_insert_id() C API function.

  • lc_messages

    Property Value
    Command-Line Format --lc-messages=name
    System Variable lc_messages
    Scope Global, Session
    Dynamic Yes
    Type String
    Default Value en_US

    The locale to use for error messages. The default is en_US. The server converts the argument to a language name and combines it with the value of lc_messages_dir to produce the location for the error message file. See Section 10.11, “Setting the Error Message Language”.

  • lc_messages_dir

    Property Value
    Command-Line Format --lc-messages-dir=dir_name
    System Variable lc_messages_dir
    Scope Global
    Dynamic No
    Type Directory name

    The directory where error messages are located. The server uses the value together with the value of lc_messages to produce the location for the error message file. See Section 10.11, “Setting the Error Message Language”.

  • lc_time_names

    Property Value
    System Variable lc_time_names
    Scope Global, Session
    Dynamic Yes
    Type String

    This variable specifies the locale that controls the language used to display day and month names and abbreviations. This variable affects the output from the DATE_FORMAT(), DAYNAME() and MONTHNAME() functions. Locale names are POSIX-style values such as 'ja_JP' or 'pt_BR'. The default value is 'en_US' regardless of your system's locale setting. For further information, see Section 10.15, “MySQL Server Locale Support”.

  • license

    Property Value
    System Variable license
    Scope Global
    Dynamic No
    Type String
    Default Value GPL

    The type of license the server has.

  • local_infile

    Property Value
    System Variable local_infile
    Scope Global
    Dynamic Yes
    Type Boolean
    Default Value ON

    This variable controls server-side LOCAL capability for LOAD DATA statements. Depending on the local_infile setting, the server refuses or permits local data loading by clients that have LOCAL enabled on the client side.

    To explicitly cause the server to refuse or permit LOAD DATA LOCAL statements (regardless of how client programs and libraries are configured at build time or runtime), start mysqld with local_infile disabled or enabled, respectively. local_infile can also be set at runtime. For more information, see Section 6.1.6, “Security Issues with LOAD DATA LOCAL”.

  • lock_wait_timeout

    Property Value
    Command-Line Format --lock-wait-timeout=#
    System Variable lock_wait_timeout
    Scope Global, Session
    Dynamic Yes
    Type Integer
    Default Value 31536000
    Minimum Value 1
    Maximum Value 31536000

    This variable specifies the timeout in seconds for attempts to acquire metadata locks. The permissible values range from 1 to 31536000 (1 year). The default is 31536000.

    This timeout applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures, and stored functions, as well as LOCK TABLES, FLUSH TABLES WITH READ LOCK, and HANDLER statements.

    This timeout does not apply to implicit accesses to system tables in the mysql database, such as grant tables modified by GRANT or REVOKE statements or table logging statements. The timeout does apply to system tables accessed directly, such as with SELECT or UPDATE.

    The timeout value applies separately for each metadata lock attempt. A given statement can require more than one lock, so it is possible for the statement to block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported.

    lock_wait_timeout does not apply to delayed inserts, which always execute with a timeout of 1 year. This is done to avoid unnecessary timeouts because a session that issues a delayed insert receives no notification of delayed insert timeouts.

  • locked_in_memory

    Property Value
    System Variable locked_in_memory
    Scope Global
    Dynamic No

    Whether mysqld was locked in memory with --memlock.

  • log

    Property Value
    Command-Line Format --log[=file_name]
    Deprecated Yes (removed in 5.6.1); use general-log
    System Variable log
    Scope Global
    Dynamic Yes
    Type File name

    This variable removed in MySQL 5.6.1. Use general_log instead.

  • log_error

    Property Value
    Command-Line Format --log-error[=file_name]
    System Variable log_error
    Scope Global
    Dynamic No
    Type File name

    The name of the error log file, or empty if the server is writing error messages to the console rather than to a named file. See Section 5.4.2, “The Error Log”.

  • log_output

    Property Value
    Command-Line Format --log-output=name
    System Variable log_output
    Scope Global
    Dynamic Yes
    Type Set
    Default Value FILE
    Valid Values

    TABLE

    FILE

    NONE

    The destination or destinations for general query log and slow query log output. The value is a list one or more comma-separated words chosen from TABLE, FILE, and NONE. TABLE selects logging to the general_log and slow_log tables in the mysql system database. FILE selects logging to log files. NONE disables logging. If NONE is present in the value, it takes precedence over any other words that are present. TABLE and FILE can both be given to select both log output destinations.

    This variable selects log output destinations, but does not enable log output. To do that, enable the general_log and slow_query_log system variables. For FILE logging, the general_log_file and slow_query_log_file system variables determine the log file locations. For more information, see Section 5.4.1, “Selecting General Query Log and Slow Query Log Output Destinations”.

  • log_queries_not_using_indexes

    Property Value
    Command-Line Format --log-queries-not-using-indexes
    System Variable log_queries_not_using_indexes
    Scope Global
    Dynamic Yes
    Type Boolean
    Default Value OFF

    Whether queries that do not use indexes are logged to the slow query log. See Section 5.4.5, “The Slow Query Log”.

  • log_slow_admin_statements

    Property Value
    Introduced 5.6.11
    System Variable log_slow_admin_statements
    Scope Global
    Dynamic Yes
    Type Boolean
    Default Value OFF

    Include slow administrative statements in the statements written to the slow query log. Administrative statements include ALTER TABLE, ANALYZE TABLE, CHECK TABLE, CREATE INDEX, DROP INDEX, OPTIMIZE TABLE, and REPAIR TABLE.

    This variable was added in MySQL 5.6.11 as a replacement for the --log-slow-admin-statements option. The system variable can be set on the command line or in option files the same way as the option, so there is no need for any changes at server startup, but the system variable also makes it possible to examine or set the value at runtime.

  • log_slow_queries

    Property Value
    Command-Line Format --log-slow-queries[=name]
    Deprecated Yes (removed in 5.6.1); use slow-query-log
    System Variable log_slow_queries
    Scope Global
    Dynamic Yes
    Type Boolean

    This variable was removed in MySQL 5.6.1. Use slow_query_log instead.

  • log_throttle_queries_not_using_indexes

    Property Value
    Introduced 5.6.5
    System Variable log_throttle_queries_not_using_indexes
    Scope Global
    Dynamic Yes
    Type Integer
    Default Value 0

    If log_queries_not_using_indexes is enabled, the log_throttle_queries_not_using_indexes variable limits the number of such queries per minute that can be written to the slow query log. A value of 0 (the default) means no limit. For more information, see Section 5.4.5, “The Slow Query Log”.

  • log_warnings

    Property Value
    Command-Line Format --log-warnings[=#]
    System Variable log_warnings
    Scope (>= 5.6.4) Global
    Scope (<= 5.6.3) Global, Session
    Dynamic Yes
    Type Integer
    Default Value 1
    Minimum Value 0
    Maximum Value (64-bit platforms) 18446744073709551615
    Maximum Value (32-bit platforms) 4294967295

    Whether to produce additional warning messages to the error log. This variable is enabled by default with a value of 1. To disable it, set it to 0. If the value is greater than 0, the server logs messages about statements that are unsafe for statement-based logging. If the value is greater than 1, the server logs aborted connections and access-denied errors for new connection attempts. See Section B.5.2.11, “Communication Errors and Aborted Connections”.

  • long_query_time

    Property Value
    Command-Line Format --long-query-time=#
    System Variable long_query_time
    Scope Global, Session
    Dynamic Yes
    Type Numeric
    Default Value 10
    Minimum Value 0

    If a query takes longer than this many seconds, the server increments the Slow_queries status variable. If the slow query log is enabled, the query is logged to the slow query log file. This value is measured in real time, not CPU time, so a query that is under the threshold on a lightly loaded system might be above the threshold on a heavily loaded one. The minimum and default values of long_query_time are 0 and 10, respectively. The value can be specified to a resolution of microseconds. For logging to a file, times are written including the microseconds part. For logging to tables, only integer times are written; the microseconds part is ignored. See Section 5.4.5, “The Slow Query Log”.

  • low_priority_updates

    Property Value
    Command-Line Format --low-priority-updates
    System Variable low_priority_updates
    Scope Global, Session
    Dynamic Yes
    Type Boolean
    Default Value FALSE

    If set to 1, all INSERT, UPDATE, DELETE, and LOCK TABLE WRITE statements wait until there is no pending SELECT or LOCK TABLE READ on the affected table. This affects only storage engines that use only table-level locking (such as MyISAM, MEMORY, and MERGE).

  • lower_case_file_system

    Property Value
    System Variable lower_case_file_system
    Scope Global
    Dynamic No
    Type Boolean

    This variable describes the case sensitivity of file names on the file system where the data directory is located. OFF means file names are case-sensitive, ON means they are not case-sensitive. This variable is read only because it reflects a file system attribute and setting it would have no effect on the file system.

  • lower_case_table_names

    Property Value
    Command-Line Format --lower-case-table-names[=#]
    System Variable lower_case_table_names
    Scope Global
    Dynamic No
    Type Integer
    Default Value 0
    Minimum Value 0
    Maximum Value 2

    If set to 0, table names are stored as specified and comparisons are case-sensitive. If set to 1, table names are stored in lowercase on disk and comparisons are not case sensitive. If set to 2, table names are stored as given but compared in lowercase. This option also applies to database names and table aliases. For additional information, see Section 9.2.2, “Identifier Case Sensitivity”.

    On Windows the default value is 1. On macOS, the default value is 2. On Linux, a value of 2 is not supported; the server forces the value to 0 instead.

    You should not set lower_case_table_names to 0 if you are running MySQL on a system where the data directory resides on a case-insensitive file system (such as on Windows or macOS). It is an unsupported combination that could result in a hang condition when running an INSERT INTO ... SELECT ... FROM tbl_name operation with the wrong tbl_name letter case. With MyISAM, accessing table names using different letter cases could cause index corruption.

    As of MySQL 5.6.27, an error message is printed and the server exits if you attempt to start the server with --lower_case_table_names=0 on a case-insensitive file system.

    If you are using InnoDB tables, you should set this variable to 1 on all platforms to force names to be converted to lowercase.

    The setting of this variable in MySQL 5.6 affects the behavior of replication filtering options with regard to case sensitivity. This is a change from previous versions of MySQL. (Bug #51639) See Section 17.2.3, “How Servers Evaluate Replication Filtering Rules”, for more information.

  • max_allowed_packet

    Property Value
    Command-Line Format --max-allowed-packet=#
    System Variable max_allowed_packet
    Scope Global, Session
    Dynamic Yes
    Type Integer
    Default Value (>= 5.6.6) 4194304
    Default Value (<= 5.6.5) 1048576
    Minimum Value 1024
    Maximum Value 1073741824

    The maximum size of one packet or any generated/intermediate string, or any parameter sent by the mysql_stmt_send_long_data() C API function. The default is 4MB.

    The packet message buffer is initialized to net_buffer_length bytes, but can grow up to max_allowed_packet bytes when needed. This value by default is small, to catch large (possibly incorrect) packets.

    You must increase this value if you are using large BLOB columns or long strings. It should be as big as the largest BLOB you want to use. The protocol limit for max_allowed_packet is 1GB. The value should be a multiple of 1024; nonmultiples are rounded down to the nearest multiple.

    When you change the message buffer size by changing the value of the max_allowed_packet variable, you should also change the buffer size on the client side if your client program permits it. The default max_allowed_packet value built in to the client library is 1GB, but individual client programs might override this. For example, mysql and mysqldump have defaults of 16MB and 24MB, respectively. They also enable you to change the client-side value by setting max_allowed_packet on the command line or in an option file.

    The session value of this variable is read only. The client can receive up to as many bytes as the session value. However, the server will not send to the client more bytes than the current global max_allowed_packet value. (The global value could be less than the session value if the global value is changed after the client connects.)

  • max_connect_errors

    Property Value
    Command-Line Format --max-connect-errors=#
    System Variable max_connect_errors
    Scope Global
    Dynamic Yes
    Type Integer
    Default Value (64-bit platforms, >= 5.6.6) 100
    Default Value (64-bit platforms, <= 5.6.5) 10
    Default Value (32-bit platforms, >= 5.6.6) 100
    Default Value (32-bit platforms, <= 5.6.5) 10
    Minimum Value 1
    Maximum Value (64-bit platforms) 18446744073709551615
    Maximum Value (32-bit platforms) 4294967295

    After