From: Adam Rich <adam.r@sbcglobal.net>
To: 'Craig A. James' <cjames@modgraph-usa.com>
To: 'Guy Rouillier' <guyr-ml1@burntmail.com>
To: 'PostgreSQL Performance' <pgsql-performance@postgresql.org>
Subject: Re: High update activity, PostgreSQL vs BigDBMS
Date: Sun, 7 Jan 2007 20:26:29 -0600
Message-ID: <022d01c732cc$69f0e2a0$6400a8c0@dualcore> (raw)
In-Reply-To: <45A188AF.5070006@modgraph-usa.com>
I'm using 8.2 and using order by & limit is still faster than MAX()
even though MAX() now seems to rewrite to an almost identical plan
internally.
Count(*) still seems to use a full table scan rather than an index scan.
Using one of our tables, MySQL/Oracle/MS-SQL all return instantly while
PG takes longer ther 700ms. Luckily we can design around this issue.
-----Original Message-----
From: pgsql-performance-owner@postgresql.org
[mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Craig A.
James
Sent: Sunday, January 07, 2007 5:57 PM
To: Guy Rouillier; PostgreSQL Performance
Subject: Re: [PERFORM] High update activity, PostgreSQL vs BigDBMS
Craig A. James wrote:
> The "idiom" to replace count() was
> "select col from tbl order by col desc limit 1". It worked miracles
for
> my app.
Sorry, I meant to write, "the idiom to replace MAX()", not count()...
MAX() was the function that was killing me, 'tho count() also gave me
problems.
Craig
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To: pgsql-performance@postgresql.org
Cc: adam.r@sbcglobal.net, cjames@modgraph-usa.com, guyr-ml1@burntmail.com
Subject: Re: High update activity, PostgreSQL vs BigDBMS
In-Reply-To: <022d01c732cc$69f0e2a0$6400a8c0@dualcore>
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