From: Greg Stark <gsstark@mit.edu>
To: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Cc: pgsql-performance@postgresql.org
Subject: Re: Good News re count(*) in 8.1
Date: 22 Feb 2006 22:52:48 -0500
Message-ID: <87irr6zq7j.fsf@stark.xeocode.com> (raw)
In-Reply-To: <43FC4384.EE98.0025.0@wicourts.gov>
References: <43FC4384.EE98.0025.0@wicourts.gov>
"Kevin Grittner" <Kevin.Grittner@wicourts.gov> writes:
> There have been several times that I have run a SELECT COUNT(*) on an entire
> table on all central machines. On identical hardware, with identical data,
> and equivalent query loads, the PostgreSQL databases have responded with a
> count in 50% to 70% of the time of the commercial product, in spite of the
> fact that the commercial product does a scan of a non-clustered index while
> PostgreSQL scans the data pages.
I take it these are fairly narrow rows? The big benefit of index-only scans
come in when you're scanning extremely wide tables, often counting rows
matching some indexed criteria.
--
greg
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To: pgsql-performance@postgresql.org
Cc: gsstark@mit.edu, Kevin.Grittner@wicourts.gov
Subject: Re: Good News re count(*) in 8.1
In-Reply-To: <87irr6zq7j.fsf@stark.xeocode.com>
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