Chapter 8 Creating J2EE Applications for BEA WebLogic

Specifying Support for Oracle

Generated primary key support for Oracle databases use Oracle's SEQUENCE. This feature works with a sequence entity in the Oracle database to generate unique primary keys. The Oracle SEQUENCE is called when a new number is needed.

Once the SEQUENCE already exists in the database, you specify automatic key generation in the XML deployment descriptors. In the weblogic-cmp-rdbms-jar.xml file, you specify automatic key generation as follows:

<automatic-key-generation>
	<generator-type>ORACLE</generator-type>
	<generator_name>test_sequence</generator-name>
	<key-cache-size>10</key-cache-size>
</automatic-key-generator>

You need to specify the name of the ORACLE SEQUENCE to be used, via the generator-name element. If the ORACLE SEQUENCE was created with an INCREMENT value, then you must specify a key-cache-size. This value must match the Oracle SEQUENCE INCREMENT value. If these two values are different, then you will most likely have duplicate key problems.

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