Re: problems with new vacuum (??)

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Barry Lind <barry(at)xythos(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: problems with new vacuum (??)
Date: 2002-01-02 18:12:03
Message-ID: 200201021812.g02IC3q09418@candle.pha.pa.us
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Tom Lane wrote:
> Barry Lind <barry(at)xythos(dot)com> writes:
> > But while this vacuum was running the rest of the system was performing
> > very poorly. Opperations that usually are subsecond, where taking
> > minutes to complete.
>
> Is this any different from the behavior of 7.1 vacuum? Also, what
> platform are you on?
>
> I've noticed on a Linux 2.4 box (RH 7.2, typical commodity-grade PC
> hardware) that vacuum, pgbench, or almost any I/O intensive operation
> drives interactive performance into the ground. I have not had an
> opportunity to try to characterize the problem, but I suspect Linux's
> disk I/O scheduler is not bright enough to prioritize interactive
> operations.

Just as a data point, I have not seen pgbench dramatically affect
performance on BSD/OS. Interactive sessions are just slightly slower
when then need to access the disk.

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