On Fri, Jun 27, 2003 at 16:35:36 +0200, Dani Oderbolz <[EMAIL PROTECTED]> wrote: > Well, why not just use the Sequence? > Is there really such a performance hit when calling a trigger?
I think the big issue is concurrency. Sequences are designed so that conncurrent uses of the sequence don't block each other. In the trigger based methods you have to lock the value against concurrent update and this lock will be held to the end of the transaction. This has the potential to really hurt your performance. I may have been misunderstanding what you are trying to do though. If your problem was that people could update or insert values into the serial column that might cause other transactions to unexpected fail (when they try to use a duplicate value - assuming you use a unique index on the column) then you could use a trigger to prevent updates on that column and force inserts to always use nextval. If you need to reload the database at some point, you will need to do something to keep the triggers from interfering with the reload. This should be fairly efficient. I had thought you were concerned about possible gaps in the sequence. ---------------------------(end of broadcast)--------------------------- TIP 7: don't forget to increase your free space map settings
