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Re: auto vacuum, not working?

From: Greg Smith <greg(at)2ndQuadrant(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: auto vacuum, not working?
Date: 2012-01-15 12:09:50
Message-ID: 4F12C20E.7080400@2ndQuadrant.com (view raw or flat)
Thread:
Lists: pgsql-performance
On 01/13/2012 07:08 AM, Anibal David Acosta wrote:
>
> How can I release the space used by deleted rows? Without block the table.
>
>

The database can only reduce the size tables by returning space to the 
operating system in one situation:  there is free space at the very end 
of the table.  In that case, if it's possible to get a brief exclusive 
lock on the table, it can shrink in size.

There are some programs available that reorganize table for goals like 
this, without having any long-lasting locks on the tables.  pg_reorg is 
the most popular example:  http://pgfoundry.org/projects/reorg/

-- 
Greg Smith   2ndQuadrant US    greg(at)2ndQuadrant(dot)com   Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com

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