You are greate Michael! Thanks. On Mon, 6 Sep 2004, Michael Paesold wrote:
> I wrote: > > > BEGIN; > > SET TRANSACTION ISOLATION LEVEL SERIALIZABLE; > > > > DELETE FROM schedule WHERE studentid = ... ; > > INSERT INTO schedule (studentid, ...) VALUES (... ); > > INSERT INTO schedule (studentid, ...) VALUES (... ); > > > > COMMIT; > > > > If you do it like in the above sql code, there is still a problem. The > > serializable checking here only works, if DELETE FROM schedule... really > > finds at least one row. If it does not, it will not recognize the > > serialization problem. So it's still possible that your programm creates > > duplicates. > > > > I have tested this here. I don't really know if this is just the case with > > PostgreSQL serializable transactions (MVCC limitation) or a general > problem. > > There is a detailed description about this problem in Section 12.2.2.1. of > the PostgreSQL 8 docs here: > http://developer.postgresql.org/docs/postgres/transaction-iso.html > > (Serializable Isolation versus True Serializability) > > Best Regards, > Michael Paesold > -- Evgeny. ---------------------------(end of broadcast)--------------------------- TIP 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])
