From: Ross J. Reedstrom <reedstrm@rice.edu>
To: pgsql-performance@postgresql.org
Subject: Re: [HACKERS] Slow count(*) again...
Date: Thu, 3 Feb 2011 13:24:42 -0600
Message-ID: <20110203192442.GF31926@rice.edu> (raw)
In-Reply-To: <87d3n92etk.fsf@cbbrowne.afilias-int.info>
References: <4D489AD1.1010105@vmsinfo.com>
<AANLkTiknZi97dDwm7sHqy0EL7tpNEP9sY5uPV6AN+q=u@mail.gmail.com>
<4D499E55.4020107@vmsinfo.com>
<4D49A6B9.4060608@2ndquadrant.com>
<4D49C482.4010707@vmsinfo.com>
<4D49F0BA.9000901@2ndquadrant.com>
<4D4A16BF.1020304@vmsinfo.com>
<4D4A4844.3020409@2ndquadrant.com>
<4D4AD9F6.6040903@vmsinfo.com>
<87d3n92etk.fsf@cbbrowne.afilias-int.info>
On Thu, Feb 03, 2011 at 12:44:23PM -0500, Chris Browne wrote:
> mladen.gogala@vmsinfo.com (Mladen Gogala) writes:
> > Hints are not even that complicated to program. The SQL parser should
> > compile the list of hints into a table and optimizer should check
> > whether any of the applicable access methods exist in the table. If it
> > does - use it. If not, ignore it. This looks to me like a
> > philosophical issue, not a programming issue.
>
> It's worth looking back to what has already been elaborated on in the
> ToDo.
>
> http://wiki.postgresql.org/wiki/Todo
> -----------------------------------
> Optimizer hints (not wanted)
>
> Optimizer hints are used to work around problems in the optimizer and
> introduce upgrade and maintenance issues. We would rather have the
> problems reported and fixed. We have discussed a more sophisticated
> system of per-class cost adjustment instead, but a specification remains
> to be developed.
And as to the 'wait around for a new version to fix that': there are
constantly excellent examples of exactly this happening, all the time
with PostgreSQL - most recent example I've seen -
http://archives.postgresql.org/pgsql-performance/2011-01/msg00337.php
The wait often isn't long, at all.
Ross
--
Ross Reedstrom, Ph.D. reedstrm@rice.edu
Systems Engineer & Admin, Research Scientist phone: 713-348-6166
Connexions http://cnx.org fax: 713-348-3665
Rice University MS-375, Houston, TX 77005
GPG Key fingerprint = F023 82C8 9B0E 2CC6 0D8E F888 D3AE 810E 88F0 BEDE
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To: pgsql-performance@postgresql.org
Cc: reedstrm@rice.edu
Subject: Re: [HACKERS] Slow count(*) again...
In-Reply-To: <20110203192442.GF31926@rice.edu>
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