From: Jan Wieck <JanWieck@Yahoo.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Bruce Momjian <pgman@candle.pha.pa.us>
Cc: pgsql-hackers@postgreSQL.org
Subject: Re: Stats collector performance improvement
Date: Mon, 02 Jan 2006 23:06:57 -0500
Message-ID: <43B9F861.5040207@Yahoo.com> (raw)
In-Reply-To: <11924.1136233224@sss.pgh.pa.us>
References: <200601021840.k02Ieed21704@candle.pha.pa.us>
<11924.1136233224@sss.pgh.pa.us>
On 1/2/2006 3:20 PM, Tom Lane wrote:
> [ moving to -hackers ]
>
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
>> I did some research on this because the numbers Tom quotes indicate there
>> is something wrong in the way we process stats_command_string
>> statistics.
>> [ ... proposed patch that seems pretty klugy to me ... ]
>
> 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 original design was geared towards searching for useless/missing
indexes and tuning activity like that. This never happened, but instead
people tried to use it as a reliable debugging or access statistics aid
... which is fine but not what it originally was intended for.
So yes, I think looking at what it usually is used for, a message
passing system like SysV message queues (puke) or similar would do a
better job.
Jan
> 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.
>
> If we abandoned the unreliable-communication approach, could we build
> something with less overhead?
>
> regards, tom lane
--
#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
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#================================================== JanWieck@Yahoo.com #
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To: pgsql-performance@postgresql.org
Cc: JanWieck@Yahoo.com, tgl@sss.pgh.pa.us, pgman@candle.pha.pa.us, pgsql-hackers@postgreSQL.org
Subject: Re: Stats collector performance improvement
In-Reply-To: <43B9F861.5040207@Yahoo.com>
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