Re: Commit takes a long time.

On Thu, 2008-01-03 at 11:35 -0500, Tom Lane wrote:
> "Peter Childs" <peterachilds(at)gmail(dot)com> writes:
> > Using Postgresql 8.1.10 every so often I get a transaction that takes a
> > while to commit.
>
> > I log everything that takes over 500ms and quite reguallly it says things
> > like
>
> > 707.036 ms statement: COMMIT
>
> AFAIK there are only two likely explanations for that:
>
> 1. You have a lot of deferred triggers that have to run at COMMIT time.
>
> 2. The disk system gets so bottlenecked that fsync'ing the commit record
> takes a long time.

I've seen 3 other reasons for this in the field while tuning people's
systems. In 8.3 we've fixed one, reduced the other and the third is
amenable to tuning via wal_buffers even in 8.1

--
Simon Riggs
2ndQuadrant http://www.2ndQuadrant.com