From: Heikki Linnakangas <heikki@enterprisedb.com>
To: Mark Woodward <pgsql@mohawksoft.com>
Cc: pg@mohawksoft.com
Cc: pgsql-hackers@postgresql.org
Subject: Re: Netflix Prize data
Date: Thu, 05 Oct 2006 09:35:01 +0100
Message-ID: <4524C3B5.8030206@enterprisedb.com> (raw)
In-Reply-To: <18350.24.91.171.78.1159994622.squirrel@mail.mohawksoft.com>
References: <18350.24.91.171.78.1159994622.squirrel@mail.mohawksoft.com>
Mark Woodward wrote:
>
> I tried to cluster the data along a particular index but had to cancel it
> after 3 hours.
If the data is in random order, it's faster to do
SELECT * INTO foo_sorted FROM foo ORDER BY bar
then CREATE INDEX, than to run CLUSTER.
That's because CLUSTER does a full index scan of the table, which is
slower than a seqscan + sort if the table is not already clustered.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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To: pgsql-hackers@postgresql.org
Cc: heikki@enterprisedb.com, pgsql@mohawksoft.com, pg@mohawksoft.com
Subject: Re: Netflix Prize data
In-Reply-To: <4524C3B5.8030206@enterprisedb.com>
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