Re: 答复: [PERFORM] Postgresql update op is very very slow

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "jay" <jackem(dot)mojx(at)alibaba-inc(dot)com>
Cc: "'Heikki Linnakangas'" <heikki(at)enterprisedb(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: 答复: [PERFORM] Postgresql update op is very very slow
Date: 2008-06-26 15:04:21
Message-ID: 16213.1214492661@sss.pgh.pa.us
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"jay" <jackem(dot)mojx(at)alibaba-inc(dot)com> writes:
> I know the problem, because there are about 35 million rows , which
> cost about 12G disk space and checkpoint segments use 64, but update
> operation is in one transaction which lead fast fill up the checkpoint
> segments and lead do checkpoints frequently, but checkpoints will cost lots
> resources, so update operation become slowly and slowly and bgwrite won't
> write because it's not commit yet.
> Create a new table maybe a quick solution, but it's not appropriated in some
> cases.
> If we can do commit very 1000 row per round, it may resolve the
> problem.

No, that's utterly unrelated. Transaction boundaries have nothing to do
with checkpoints.

regards, tom lane

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