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34 lines
1.0 KiB
Plaintext
34 lines
1.0 KiB
Plaintext
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.\" This is -*-nroff-*-
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.\" XXX standard disclaimer belongs here....
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.\" $Header: /cvsroot/pgsql/doc/man/Attic/cluster.l,v 1.1.1.1 1996/08/18 22:14:20 scrappy Exp $
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.TH CLUSTER SQL 01/23/93 Postgres95 Postgres95
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.SH NAME
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cluster \(em give storage clustering advice to Postgres
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.SH SYNOPSIS
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.nf
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\fBcluster\fR indexname \fBon\fR attname
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.fi
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.SH DESCRIPTION
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This command instructs Postgres to cluster the class specified by
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.IR classname
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approximately based on the index specified by
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.IR indexname.
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The index must already have been defined on
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.IR classname.
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.PP
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When a class is clustered, it is physically reordered based on the index
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information. The clustering is static. In other words, if the class is
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updated, it may become unclustered. No attempt is made to keep new
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instances or updated tuples clustered. If desired, the user can
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recluster manually by issuing the command again.
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.SH EXAMPLE
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.nf
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/*
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* cluster employees in based on its salary attribute
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*/
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create index emp_ind on emp using btree (salary int4_ops);
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cluster emp_ind on emp
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.fi
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