Re: controlling autovacuum during the day.

On Wed, Dec 17, 2008 at 09:47:23AM -0500, Tom Lane wrote:
> "John Lister" <john.lister-ps@kickstone.com> 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.

--
Michael Fuhr