From: Qingqing Zhou <zhouqq@cs.toronto.edu>
To: pgsql-hackers@postgresql.org
Subject: Re: Stats collector performance improvement
Date: Mon, 2 Jan 2006 16:03:20 -0500
Message-ID: <dpc4cg$lm6$1@news.hub.org> (raw)
References: <200601021840.k02Ieed21704@candle.pha.pa.us>
<11924.1136233224@sss.pgh.pa.us>
"Tom Lane" <tgl@sss.pgh.pa.us> wrote
>
> I wonder whether we shouldn't consider something more drastic, like
> getting rid of the intermediate stats buffer process entirely.
>
> The original design for the stats communication code was based on the
> premise that it's better to drop data than to make backends wait on
> the stats collector. However, as things have turned out I think this
> notion is a flop: the people who are using stats at all want the stats
> to be reliable. We've certainly seen plenty of gripes from people who
> are unhappy that backend-exit messages got dropped, and anyone who's
> using autovacuum would really like the tuple update counts to be pretty
> solid too.
>
AFAICS if we can maintain the stats counts solid, then it may hurt
performance dramatically. Think if we maintain
pgstat_count_heap_insert()/pgstat_count_heap_delete() pretty well, then we
get a replacement of count(*). To do so, I believe that will add another
lock contention on the target table stats.
Regards,
Qingqing
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To: pgsql-performance@postgresql.org
Cc: zhouqq@cs.toronto.edu, pgsql-hackers@postgresql.org
Subject: Re: Stats collector performance improvement
In-Reply-To: <dpc4cg$lm6$1@news.hub.org>
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