From: Jim C. Nasby <jnasby@pervasive.com>
To: Simon Riggs <simon@2ndquadrant.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Qingqing Zhou <zhouqq@cs.toronto.edu>
Cc: pgsql-hackers@postgresql.org
Subject: Re: Stats collector performance improvement
Date: Tue, 3 Jan 2006 10:35:56 -0600
Message-ID: <20060103163556.GH82560@pervasive.com> (raw)
In-Reply-To: <1136281253.5052.113.camel@localhost.localdomain>
References: <200601021840.k02Ieed21704@candle.pha.pa.us>
<11924.1136233224@sss.pgh.pa.us>
<dpc4cg$lm6$1@news.hub.org>
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<1136281253.5052.113.camel@localhost.localdomain>
On Tue, Jan 03, 2006 at 09:40:53AM +0000, Simon Riggs wrote:
> On Mon, 2006-01-02 at 16:48 -0500, Tom Lane wrote:
> We can also save lots of cycles on the current statement overhead, which
> is currently the worst part of the stats, performance-wise. That
> definitely needs redesign. AFAICS we only ever need to know the SQL
> statement via the stats system if the statement has been running for
> more than a few minutes - the main use case is for an admin to be able
> to diagnose a rogue or hung statement. Pushing the statement to stats
> every time is just a big overhead. That suggests we should either have a
> pull or a deferred push (longer-than-X-secs) approach.
I would argue that minutes is too long, but of course this could be
user-adjustable. I suspect that even waiting just a second could be a
huge win, since this only matters if you're executing a lot of
statements and you won't be doing that if those statements are taking
more than a second or two to execute.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
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To: pgsql-performance@postgresql.org
Cc: jnasby@pervasive.com, simon@2ndquadrant.com, tgl@sss.pgh.pa.us, zhouqq@cs.toronto.edu, pgsql-hackers@postgresql.org
Subject: Re: Stats collector performance improvement
In-Reply-To: <20060103163556.GH82560@pervasive.com>
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