On Thu, Sep 17, 2009 at 07:47:13AM -0700, rawi wrote: > > > Leo Mannhart wrote: > > > > Caveat: If you use the standard sequence generator in hibernate, it is > > not using the postgres-sequence in the "usual" manner. hibernate itself > > caches 50 ID's as sequence numbers by default. This means, hibernate > > only does a select on the database sequence every 50 numbers. it > > multyplies the database sequence by 50 to get the "real" sequence > > number. it generates the sequence numbers in blocks of 50 numbers or > > according to the sequence cache size. > > That said, you would probably not see any performance bottlenecks > > because of the sequence number generator in the database, even with > > thousands of inserts per second. > > > > Hi Leo, thank you for the explanation! > > I don't know if it is that cool to lose up to 50 IDs on each session-end of > Hibernate... > And what do you suppose it would happen, if I set the cache size of > Hibernate's own sequence (after generation) by hand to 1 instead of 50? I > wouldn't need tausends of inserts per second... > > Kind regards, Rawi > Hi Rawi,
If hibernate manages its pool of 50, it can use much lighter-weight processes than using a full SQL query to a database. I would recommend leaving it be. You can afford to lose a few ids in 2**63. Regards, Ken -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
