From: Tom Lane <tgl@sss.pgh.pa.us>
To: C. Bensend <benny@bennyvision.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: Impact of foreign keys on a simple count(*) ?
Date: Fri, 08 Oct 2004 23:49:23 -0400
Message-ID: <23596.1097293763@sss.pgh.pa.us> (raw)
In-Reply-To: <51319.63.227.74.41.1097293075.squirrel@63.227.74.41>
References: <51319.63.227.74.41.1097293075.squirrel@63.227.74.41>
"C. Bensend" <benny@bennyvision.com> writes:
> Is it the addition of the multiple foreign keys that is slowing this
> down so much?
Foreign keys have zero, nada, zilch to do with the performance of
count(*). The only plausible theory I can think of for the performance
difference is that in your "new" database the table has been through
several mass updates, leading to a whole lot of dead rows and a much
larger physical table size to scan through. I'd suggest a VACUUM
VERBOSE on both old and new copies of the table to get an idea of the
relative physical sizes. You might need a VACUUM FULL to get the new
table back down to a reasonable size...
regards, tom lane
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To: pgsql-sql@postgresql.org
Cc: tgl@sss.pgh.pa.us, benny@bennyvision.com
Subject: Re: Impact of foreign keys on a simple count(*) ?
In-Reply-To: <23596.1097293763@sss.pgh.pa.us>
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