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Re: VACUUMs take twice as long across all nodes

From: Gavin Hamill <gdh(at)laterooms(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: VACUUMs take twice as long across all nodes
Date: 2006-10-26 15:06:09
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
On Thu, 26 Oct 2006 10:47:21 -0400
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Gavin Hamill <gdh(at)laterooms(dot)com> writes:
> > Nodes 2 and 3 take only the tables necessary to run our search (10
> > out of the full 130) and are much lighter (only 7GB on disk cf.
> > 30GB for the full master) , yet the nightly VACUUM FULL has jumped
> > from 2 hours to 4 in the space of one day!
> I guess the most useful question to ask is "why are you doing VACUUM
> FULL?" Plain VACUUM should be considerably faster, and for the level
> of row turnover shown by your log, there doesn't seem to be a reason
> to use FULL.

I do FULL on the 'light' clients simply because 'I can'. The example
posted was a poor choice - the other tables have a larger churn.

Anyway, once it starts, the load balancer takes it out of rotation so
no love is lost.

The same behaviour is shown on the 'heavy' clients (master + 2 slaves)
which take all tables - although I cannot afford to VACUUM FULL on
there, the usual VACUUM ANALYZE has begun to take vastly more time
since yesterday than in the many previous months we've been using pg.


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