user manual

194 BES Developer’s Guide

Implementing primary key generation by the CMP engine

<prop-name>autoPkGenerator</prop-name>

<prop-type>java.lang.String</prop-type>

<prop-value>NAMEDSEQUENCETABLE</prop-value>

</property>

<prop-name>namedSequenceTableName</prop-name>

<prop-type>java.lang.String</prop-type>

<prop-value>TAB_A_SEQ</prop-value>

</property>

<prop-name>keyCacheSize</prop-name>

<prop-type>java.lang.Integer</prop-type>

<prop-value>2</prop-value>

</property>

</column-properties>

......

</table-properties>

Note that "ID" is the primary key column, which is marked for auto Pk

Generation using NAMEDSEQUENCETABLE. The table used is TAB_A_SEQ.

Note Set the ejb.CacheCreate property to false while using getPrimaryKeyAfterInsert

or useGetGeneratedKeys. The container needs to know the primary key to

dispatch calls to the bean instance. Therefore, it needs to know the primary

key at the same time the Create method returns.

Key cache size

When generating the primary key, the container fetches the key from the table

in the database. You can improve performance by reducing trips to the

database by specifying a key cache size. To use this feature, in the ejb-

borland.xml file, you set the <key-cache-size> element to specify how many

primary key values the database will fetch. The container will cache the

number of keys used for primary key generation when the value of the cache

size is > 1.

The default value for key cache size, if not specified, is 1. Although key cache

size is optional, it is recommended you specify a value > 1 to utilize

performance optimization.

Note There may be gaps in the keys generated if the container is rebooted or used

in a clustered mode.