Re: [GENERAL] Joins and links

From: David Warnock <david(at)sundayta(dot)co(dot)uk>
To: Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us>
Cc: Leon <leon(at)udmnet(dot)ru>, pgsql-general <pgsql-general(at)postgresql(dot)org>
Subject: Re: [GENERAL] Joins and links
Date: 1999-07-05 16:02:36
Message-ID: 3780D71C.12AEA967@sundayta.co.uk
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Bruce,

I did not know Postgresql had that. I have just looked at the docs and
it seems that the postgresql CLUSTER is similar to the feature in MS SQL
Server but at present is rather more limited as

a) It is static whereas CLUSTER can be set as an attribute on an index
in MS SQL Server and then ther index is not created separately the table
is kept permanently sorted by the index. This obviously is very very
slow if you add to the middle of the index and wasteful of space if you
delete rows from the table. However, for a sequential ID it is supposed
to work well.

b) as the Postgresql CLUSTER is static it does not replace the index.

I should say at this point that I never actually used the CLUSTER
feature in MS SQL Server as we decided not to use that product after
evaluating it. So I have no practical experience to know how much of the
speed improvement wanted by Leon it would deliver.

Dave
--
David Warnock
Sundayta Ltd

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