Re: Postgres Replaying WAL slowly

Jeff Frost <jeff@pgexperts.com> writes:
> On Jun 30, 2014, at 1:15 PM, Andres Freund <andres@2ndquadrant.com> wrote:
>> So these are probably relations created in uncommitted
>> transactions. Possibly ON COMMIT DROP temp tables?

> That would make sense.  There are definitely quite a few of those being used.

Uh-huh.  I doubt that the mechanism that handles propagation of
AccessExclusiveLocks to the standby is smart enough to ignore locks
on temp tables :-(

> Another item of note is the system catalogs are quite bloated:
> Would that cause the replica to spin on StandbyReleaseLocks?

AFAIK, no.  It's an unsurprising consequence of heavy use of short-lived
temp tables though.

So it seems like we have a candidate explanation.  I'm a bit surprised
that StandbyReleaseLocks would get this slow if there are only a dozen
AccessExclusiveLocks in place at any one time, though.  Perhaps that
was a low point and there are often many more?

            regards, tom lane