E Oracle XML DB Restrictions

This appendix describes the restrictions associated with Oracle XML DB.

• Replication – Oracle XML DB does not support replication of XMLType tables.

• Extending Resource Metadata Properties – You cannot extend the resource schema. However, you can set and access custom properties belonging to other namespaces, other than XDBResource.xsd, using DOM operations on the <Resource> document.

• References Within Scalars – Oracle does not support references within a scalar, XMLType, or LOB data column.

• Thin JDBC Driver Not Supported by Some XMLType Functions – Methods extract(), transform(), and existsNode() work only with the thick JDBC driver. Not all oracle.xdb.XMLType functions are supported by the thin JDBC driver. If you do not use oracle.xdb.XMLType classes and the OCI driver, you could lose performance benefits.

• NVARCHAR and NCHAR SQLTypes Not Supported – Oracle XML DB does not support NVARCHAR or NCHAR as a SQLType when registering an XML schema. In other words in the XML schema file (.xsd) you cannot specify that an element should be of type NVARCHAR or NCHAR. Also, if you provide your own type you should not use these datatypes.

• Identifier Length Limited to 4000 Characters – Oracle XML DB supports only XML identifiers that are 4000 characters long, or shorter.

• 64K Limit on Text Nodes and Attribute Values – Each text node or attribute value processed by Oracle XML DB is limited in size to 64K bytes.