I'm trying to debug a problem from customer log files. (I'm not able to reproduce the problem.) I can see several things wrong with our code, but would like to know whether, and how, those problems could cause these symptoms.

This is hibernate 3.3.2 with mysql 5.1, on Windows.

My table's mapping specifies generator increment. This is bad because we're running in a clustered environment. We have seen a few duplicate key errors which I understand could be caused by this.

The database table has its ID column defined as auto_increment. I understand this is nonsensical because hibernate is going to create the IDs, so the database auto_increment will not actually be used.

The error I don't understand is this:

org.springframework.dao.DataIntegrityViolationException: Could not execute JDBC batch update; SQL [insert into MY_TABLE(col1, col2, col3, col4, ID_) values (?, ?, ?, ?, ?)]; constraint [null]

I've looked very closely at my code, and I don't see any way that any of the values coming from my application could be null, so I'm wondering if hibernate could possibly be passing in a null ID? Is there any scenario where this could happen?

Thanks for your help!

If you use auto increment on database, then you have to use native generator instead of increment.