I have a java tool which is executing insert statement in batch, but after some 250000 records it says that could not insert new rows. Not enough core.

When I have less records say (1000) it insert the records.

can anybody help what is this core and how to clear it. Is it java side error or the informix error.

It might be an expected behaviour from informix in the case you are hitting a long transaction. This happens when the number of opérations within a single transaction exeeds the configured size of the logical log. Your application should receive a -458 Error, and in the engine log file you should see something like "Aborting Long Transaction: tx 0xHHHHHHHH username: user_name"
In this case, the solution is to add logical logs to the engine until the transaction succeeds.

If you don't have this error, this is probably a java side error, and I can't do anything for you :-(

Hope this helps