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CLUSTER command

From: Jean-Luc Lachance <jllachan(at)nsd(dot)ca>
To: pgsql-general(at)postgresql(dot)org
Cc: pgsql-performance(at)postgresql(dot)org
Subject: CLUSTER command
Date: 2002-12-12 21:31:46
Message-ID: 3DF90042.E5290B7F@nsd.ca (view raw or flat)
Thread:
Lists: pgsql-generalpgsql-interfacespgsql-performance
Hi all,

I just read about the cluster command and was a little (very)
disapointed.
Clustered tables do not remain clustered after inserts.
Clustered tables are usefull when the table is very large and there are
few different keys.


Because the table file is already extended (2G limit) using different
files extension (.N)
how complicated (modifying the code) would it be to have the table files
split according to the cluster key?

This would:

Greatly improve performance when the cluster key in included in search
criteria.
Allow for a much larger table before a file has to be split (.N).
Simplify the management of symblinks (that's something else we need to
look at).
The index file for that field would no longer be required.

Of course, there should be only one cluster key per table.
The length the "key" should be short and the number of unique key should
be low as well.

SO... ?

JLL

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