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Oracle® Database Reference
10g Release 2 (10.2)

Part Number B14237-04
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Datatype Limits

Datatypes Limit Comments
BFILE Maximum size: 4 GB

Maximum size of a file name: 255 characters

Maximum size of a directory name: 30 characters

Maximum number of open BFILEs: see Comments

The maximum number of BFILEs is limited by the value of the SESSION_MAX_OPEN_FILES initialization parameter, which is itself limited by the maximum number of open files the operating system will allow.
BLOB Maximum size: (4 GB - 1) * DB_BLOCK_SIZE initialization parameter (8 TB to 128 TB) The number of LOB columns per table is limited only by the maximum number of columns per table (that is, 1000Foot 1 ).
CHAR Maximum size: 2000 bytes  
CHAR VARYING Maximum size: 4000 bytes  
CLOB Maximum size: (4 GB - 1) * DB_BLOCK_SIZE initialization parameter (8 TB to 128 TB) The number of LOB columns per table is limited only by the maximum number of columns per table (that is, 1000Footref 1).
Literals (characters or numbers in SQL or PL/SQL) Maximum size: 4000 characters  
LONG Maximum size: 2 GB - 1 Only one LONG column is allowed per table.
NCHAR Maximum size: 2000 bytes  
NCHAR VARYING Maximum size: 4000 bytes  
NCLOB Maximum size: (4 GB - 1) * DB_BLOCK_SIZE initialization parameter (8 TB to 128 TB) The number of LOB columns per table is limited only by the maximum number of columns per table (that is, 1000Footref 1).
NUMBER 999...(38 9's) x10125 maximum value Can be represented to full 38-digit precision (the mantissa).
-999...(38 9's) x10125 minimum value Can be represented to full 38-digit precision (the mantissa).
Precision 38 significant digits  
RAW Maximum size: 2000 bytes  
VARCHAR Maximum size: 4000 bytes  
VARCHAR2 Maximum size: 4000 bytes  

Footnote 1 The absolute maximum number of columns in a table is 1000. However, when you create an object table (or a relational table with columns of object, nested table, varray, or REF type), Oracle maps the columns of the user-defined types to relational columns, creating in effect hidden columns that count toward the 1000-column limit. For details on how Oracle calculates the total number of columns in such a table, refer to Oracle Database Administrator's Guide.

See Also:

Oracle Database SQL Reference for information on the rules and limitations governing the use of datatypes and naming database objects