On Fri, 2009-09-25 at 13:23 +0300, Heikki Linnakangas wrote: > Simon Riggs wrote: > > On Wed, 2009-09-23 at 17:45 +0300, Heikki Linnakangas wrote: > >> XactClearRecoveryTransactions() when we see a shutdown checkpoint, which > >> clears all recovery locks. But doesn't that prematurely clear all locks > >> belonging to prepared transactions as well? > > > > Much better to read your second post(s). :-) > > > > Yes, you have found a(nother) issue. This was the first one that gave me > > pause to think of the answer. The locks currently aren't tracked as to > > whether they are 2PC or not, so we would need to store that info also so > > that we can selectively release locks later. > > > > Question: is it possible to do a fast shutdown when we have a prepared > > transaction? > > Yes. > > > Would it be better to take a different approach there for > > prepared transactions? It seems strange to write a shutdown checkpoint > > when the system isn't yet "clean". > > Hmm, I guess you could define prepared transactions as active backends > from the shutdown point of view, and wait for them to finish. I can see > one problem, though: Once you issue shutdown, fast or smart, we no > longer accept new connections. So you can't connect to issue the > ROLLBACK/COMMIT PREPARED anymore. Anyway, it would be a change from the > current behavior, so it would be better to cope with prepared > transactions in the standby.
Definitely need to cope with them for Hot Standby. My point was general one to say that behaviour is very non-useful for users with prepared transactions. It just causes manual effort by a DBA each time the system is shutdown. -- Simon Riggs www.2ndQuadrant.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
