Hibernate Delete Error: Batch Update Returned Unexpected Row Count

Question

I wrote this method below that is suppose to delete a member record from the database. But when I use it in my servlet it returns an error.

MemberDao Class

Answer 1

I have had this problem,

I checked my code, there weren't any problems but when i checked my data I found out, I had two entities with the same id!

So, the flush() could not work, because it works one by one for batch updates and it found 2 rows. Therefore, it didn't update and threw exception, but it was my problem. I don't know if it works fine for you or not!

Answer 2

I experienced this same issue with hibernate/JPA 2.1 when using memcached as the secondary cache. You would get the above exception along with a StaleStateException. The resolution was different than what has been noted previously.

I noticed that if you have an operation that interleaves deletes and selects (finds) from within the same table and transaction, hibernate can become overwhelmed and report that stale state exception. It would only occur for us during production as multiple identical operations on different entities would occur on the same table. You would see the system timeout and toss exceptions.

The solution is to simply be more efficient. Rather than interleaving in a loop, attempt to resolve which items need to be read and do so, preferably in one operation. Then perform the delete in a separate operation. Again, all in the same transaction but don't pepper hibernate with read/delete/read/delete operations.

This is much faster and reduces the housekeeping load on Hibernate considerably. The problem went away. This occurs when you are using a secondary cache and won't occur otherwise as the load will be on the database for resolution without a secondary cache. That's another issue.