From: Tom Lane <tgl@sss.pgh.pa.us>
To: Paul Lathrop <plathrop@squaretrade.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Defining performance.
Date: Thu, 30 Nov 2006 19:26:36 -0500
Message-ID: <8312.1164932796@sss.pgh.pa.us> (raw)
In-Reply-To: <456F624F.2090906@squaretrade.com>
References: <456F624F.2090906@squaretrade.com>
Paul Lathrop <plathrop@squaretrade.com> writes:
> ... When I joined the company last year, the databases were
> deployed on 12-disk RAID5 arrays on dual-proc AMD machines with 4Gb of
> RAM, running Debian Woody and Postgres 7.2. These systems seemed to
> suffer a gradually decreasing performance accompanied by a gradually
> growing disk space usage. The DBA had come to the conclusion that the
> VACUUM command did/does not work on these systems, because even after a
> VACUUM FULL, the size of the database was continually increasing.
The very first thing you need to do is get off 7.2.
After that, I'd recommend looking at *not* using VACUUM FULL. FULL is
actually counterproductive in a lot of scenarios, because it shrinks the
tables at the price of bloating the indexes. And 7.2's poor ability to
reuse index space turns that into a double whammy. Have you checked
into the relative sizes of tables and indexes and tracked the trend over
time?
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, plathrop@squaretrade.com
Subject: Re: Defining performance.
In-Reply-To: <8312.1164932796@sss.pgh.pa.us>
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