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Re: sql-bench

From: Scott Marlowe <smarlowe(at)g2switchworks(dot)com>
To: Merlin Moncure <mmoncure(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, yoav x <yoav112003(at)yahoo(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: sql-bench
Date: 2006-09-13 21:10:25
Message-ID: 1158181825.24726.4.camel@state.g2switchworks.com (view raw or flat)
Thread:
Lists: pgsql-performance
On Wed, 2006-09-13 at 14:36, Merlin Moncure wrote:
> On 9/13/06, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > IIRC, with these settings PG 8.0 seemed to be about half the speed of
> > mysql 5.0 w/myisam, which is probably somewhere in the ballpark of the
> > truth for tests of this nature, ie, single query stream of fairly simple
> > queries.  If you try concurrent-update scenarios or something that
> > stresses planning ability you may arrive at different results though.
> > I have not retested with more recent versions.
> 
> if postgresql uses prepared statements for such queries, it will
> roughly tie mysql/myisam in raw query output on this type of load
> which also happens to be very easy to prepare...afaik mysql gets zero
> performance benefit from preparing statements   This is extremely
> trivial to test&confirm even on a shell script. [aside: will this
> still be the case if peter e's planner changes become reality?]
> 
> another cheater trick benchmarkers do to disparage postgresql is to
> not run analyze intentionally.  Basically all production postgresql
> systems of any size will run analyze on cron.
> 
> another small aside, I caught the sqlite people actually *detuning*
> postgresql for performance by turning stats_command_string=on in
> postgresql.conf.  The way it was portrayed it almost looked like
> cheating.  I busted them on it (go to
> http://www.sqlite.org/cvstrac/wiki?p=SpeedComparison and look for the
> remarks right below the results)

They're running autovacuum, which requires that, doesn't it?

I'd rather them be running autovacuum than not vacuuming / analyzing at
all.  And autovacuum is a pretty realistic setting for most databases (I
use it on my production machines.)

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