[ General removed, hackers added.] Where are we on nested transactions. Is it something we can get for 7.5?
--------------------------------------------------------------------------- Manfred Koizar wrote: > On Wed, 3 Dec 2003 08:08:49 -0000 (GMT), "John Sidney-Woollett" > <[EMAIL PROTECTED]> wrote: > >Issue - nested transactions > > >This is an issue for us because some procedures make use of a function > >which issues a row level lock on a table (select ... for update) in order > >to read and then update a counter, and which then commits to release the > >lock. The nested function returns the new counter value on return. > > AFAICS nested transactions - at least in the way we plan to implement > them - won't help, because subtransaction commit will not release locks. > We see a subtransaction as part of the main transaction. If a > subtransaction commits but the main transaction aborts, the > subtransaction's effects are rolled back. > > START TRANSACTION; -- main xact > ... > START TRANSACTION; -- sub xact > UPDATE t SET n=n+1 WHERE i=42; > > This locks the row with i=42, because if another transaction wants to > update this row, it cannot know whether to start with the old or the new > value of n before our transaction commits or rolls back. > > COMMIT; --sub xact > > Here we are still in the main transaction. Nothing has changed for > other backends, because they still don't know whether our main > transaction will succeed or fail. So we have to keep the lock... > > >Is there a simple/elegant solution to this problem? > > Perhaps dblink? Just a thought, I don't have any personal experience > with it. > > Servus > Manfred > > ---------------------------(end of broadcast)--------------------------- > TIP 2: you can get off all lists at once with the unregister command > (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED]) > -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 ---------------------------(end of broadcast)--------------------------- TIP 7: don't forget to increase your free space map settings
