This FAQ above (http://www.hibernate.org/120.html#A6) regarding batch 
updates should be disabled against DB2 is incorrect. Batch update works 
fine when using IBM DB2 JDBC driver shipped with version 8 and version 
9. Batch updates should be enabled because it provides performance 
advantages to application using hibernate against DB2.

In another thread (http://www.hibernate.org/120.741.html) it shows a 
stack trace with ClassCastException. This only happens if type changes 
between batch elements. This can be avoided by setting connection 
property deferPrepares to false. This bug was also fixed in the driver 
that was shipped in early 2006.