On Sunday, November 15, 2009, Simon Riggs <si...@2ndquadrant.com> wrote: > On Sun, 2009-11-15 at 10:00 +0100, Magnus Hagander wrote: > >> What does the time depend on? > > We need to wait for all current transactions to complete. (i.e. any > backend that has (or could) take an xid or an AccessExclusiveLock before > it commits.). Similar-ish to the wait for a CREATE INDEX CONCURRENTLY. > > The standby already performs this wait in the case where we overflow the > snapshot, so we have >64 subtransactions on *any* current transaction on > the master. The reason for that is (again) performance on master: we > choose not to WAL log new subtransactions. > > There are various ways around this and I'm certain we'll come up with > something ingenious but my main point is that we don't need to wait for > this issue to be solved in order for HS to be usable.
Yeah, with that explanation (thanks for clearing it up) I agree - it will definitely still be hugely useful even with this restriction, so we realy don't need to delay an initial (or the alpha at least) commit. Thus, +1 on the second one as well :) -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/ -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
