Thanks for these replys guys!

I spoke about committing every "n" retrieved rows because I observed
that DB2 driver (not JayBird...) is having a memory pb in that case.
It certainly caches things into memory, and this must be flushed
from time to time.

Before doing the select, I called setAutomCommit(false) and it
performs now 50x faster...
But, to be honnest, I do not fully understand what is the action of
setAutoCommit(true) when using a SELECT statement, which is not an
update. Is it for transaction modes differents from TRANSACTION_NONE?

Phil.