Re: When does CLUSTER occur? - Mailing list pgsql-general

From Schnabel, Robert D.
Subject Re: When does CLUSTER occur?
Date
Msg-id C20A71F48B88EF419C0DC4A5514984462814B5@UM-MBX-N03.um.umsystem.edu
Whole thread Raw
In response to Re: When does CLUSTER occur?  (Jeff Janes <jeff.janes@gmail.com>)
List pgsql-general

-----Original Message-----
From: Jeff Janes [mailto:jeff.janes@gmail.com]
Sent: Thursday, November 29, 2012 11:19 AM
To: Schnabel, Robert D.
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] When does CLUSTER occur?

On Thu, Nov 29, 2012 at 8:11 AM, Schnabel, Robert D.
<schnabelr@missouri.edu> wrote:

> My question is whether or not the "ALTER TABLE gen1011 CLUSTER ON
> xgen1011_si_sn" actually clusters the table at that point or if it
> just tells it to use that index for clustering?

It just marks it to use that index if/when it is clustered, it doesn't do the clustering.


Cheers,

Jeff
[Schnabel, Robert D.]
That's what I thought because I just went through this exercise for another table which was previously clustered.  The
correlationon the column for the index was 1.  After I did the drop index, insert data, create index with the cluster
commandthe correlation was <1. 

Thanks for the clarification.

Bob


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