On Wed, 2008-12-17 at 13:31 -0300, Alvaro Herrera wrote: > Michael Fuhr wrote: > > On Wed, Dec 17, 2008 at 09:47:23AM -0500, Tom Lane wrote: > > > "John Lister" <john.lister-ps@xxxxxxxxxxxxx> writes: > > > > Cheers for the quick reply. I've tweaked them quite a bit, but we have quite > > > > a few heavily updated tables that i'd like vacuuming to keep them in check. > > > > Unfortunately the autovacuum does a FULL vacuum every so often locking the > > > > tables for quite a long time, i'd like to move these to the evening if > > > > possible. > > > > > > Huh? Autovacuum *never* does VACUUM FULL. > > > > Perhaps autovacuum is shrinking the table after finding lots of empty > > pages at the end, as in what VACUUM VERBOSE is logging here: > > > > INFO: "foo": truncated 11944384 to 8877366 pages > > > > I think this acquires an AccessExclusiveLock. I've seen this take > > hours in the case of a table with a lot of empty pages. > > There was a bug in earlier versions which caused lazy vacuum to do > cost-based delays during this phase, which caused the lock to be held > for ridiculous lengths of time. This was fixed in 8.2.something; it > shouldn't sleep anymore, but it does need to scan those pages in order > to truncate, so it can still take a while. Does this mean that if you are using autovac on 8.1, you should not use the cost delay feature? -- Brad Nicholson 416-673-4106 Database Administrator, Afilias Canada Corp. -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
