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Re: [PG 8.1.0 / AIX 5.3] Vacuum processes freezing

From: "Simon Riggs" <simon(at)2ndquadrant(dot)com>
To: RESTOUX, Loïc <loic(dot)restoux(at)capgemini(dot)com>
Cc: <pgsql-performance(at)postgresql(dot)org>
Subject: Re: [PG 8.1.0 / AIX 5.3] Vacuum processes freezing
Date: 2007-06-14 15:23:23
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
On Wed, 2007-06-13 at 18:33 +0200, RESTOUX, Loïc wrote:

> 2) I believed that the poor performances during the vacuum freeze were due to the obsolete data statistics. But after a full restart of the dabatase, performances are good. Does PostgreSQL rebuild his statistics during startup ? 

You probably don't need to run VACUUM FREEZE.

VACUUM FREEZE will thrash the disks much more than normal VACUUM. We're
improving that somewhat in 8.3, but the basic issue is that VACUUM
FREEZE cleans out more dead rows and so will dirty more data blocks.

Are you concurrently running DDL, Truncate or CLUSTER? That will
interfere with the operation of VACUUM.

  Simon Riggs             

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