On Tue, 2008-09-16 at 10:11 -0400, Alvaro Herrera wrote: > Heikki Linnakangas wrote: > > Simon Riggs wrote: > >> Subtransactions cause a couple of problems for Hot Standby: > > > > Do we need to treat subtransactions any differently from normal > > transactions? Just treat all subtransactions as top-level transactions > > until commit, and mark them all as committed when you see the commit > > record for the top-level transaction. > > This could lead to inconsistent results -- some of the subtransactions > could be marked as committed while others are still in progress. Unless > we want to be able to atomically mark them all as committed, but I don't > think that's really an option because it could mean holding the clog > lock for a long time, possibly involving I/O of clog pages.
If we did that we would need to mark them all subcomitted and then mark them all committed. So its possible, but not desirable. > I wonder if the improved clog API required to mark multiple > transactions > as committed at once would be also useful to TransactionIdCommitTree > which is used in regular transaction commit. Yes, I think its an improvement for regular commits/subcommits also. -- Simon Riggs www.2ndQuadrant.com PostgreSQL Training, Services and Support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
