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Measuring degredation of CLUSTER INDEX operation

From: Bryce Nesbitt <bryce2(at)obviously(dot)com>
To: pgsql-sql(at)postgresql(dot)org
Subject: Measuring degredation of CLUSTER INDEX operation
Date: 2008-11-10 19:54:46
Message-ID: 49189186.4070805@obviously.com (view raw or flat)
Thread:
Lists: pgsql-sql
I've got a table for which "CLUSTER tablename USING index" makes an 
order of magnitude difference.

Are there ways to determine how "unclustered" this table becomes over 
time, so I can schedule downtime to recluster?  I could use the pg_stat 
tables, but this seems awkward.

                -Bryce

NB: For manual optimization work, it would be handy to have a feature in 
"ANALYZE VERBOSE" which gives a measure from 0-100%, right next to the 
"rows examined".  100% would be an optimally clustered result.  0% would 
be every row came from a distinct block on disc.

Related links:
http://www.postgresql.org/docs/8.3/static/sql-cluster.html
http://www.postgresonline.com/journal/index.php?/archives/10-How-does-CLUSTER-ON-improve-index-performance.html


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Next:From: Scott MarloweDate: 2008-11-10 23:37:29
Subject: Re: Measuring degredation of CLUSTER INDEX operation
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Subject: Re: Subsorting GROUP BY data

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