From: Rafael Martinez <r.m.guerrero@usit.uio.no>
To: Heikki Linnakangas <heikki@enterprisedb.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Need to run CLUSTER to keep performance
Date: Tue, 13 Nov 2007 09:49:43 +0100
Message-ID: <47396527.5090801@usit.uio.no> (raw)
In-Reply-To: <47387FED.8090408@enterprisedb.com>
References: <4732E6B4.1030907@usit.uio.no>
<4732EF07.3060807@enterprisedb.com>
<47332200.9050705@usit.uio.no>
<24775.1194535980@sss.pgh.pa.us>
<4738735B.6030408@usit.uio.no>
<47387FED.8090408@enterprisedb.com>
Heikki Linnakangas wrote:
> Rafael Martinez wrote:
>> DETAIL: 83623 dead row versions cannot be removed yet.
>
> Looks like you have a long-running transaction in the background, so
> VACUUM can't remove all dead tuples. I didn't see that in the vacuum
> verbose outputs you sent earlier. Is there any backends in "Idle in
> transaction" state, if you run ps?
>
I don't see any long transaction in progress (<IDLE> in transaction) and
if we run the vacuum jobb manual just after checking this, it still
cannot remove the dead rows.
Any suggestions cause vacuum cannot remove these dead rows?
> In 8.1, CLUSTER will remove those tuples anyway, but it's actually not
> correct.
With other words, .... we have to be very carefull to not run CLUSTER on
a table been modified inside a transaction if we do not want to lose
data? ...
Does this mean that if we run a transaction which update/delete many
rows, run cluster before the transaction is finnish, and then rollback
the transaction after cluster has been executed, all dead rows
updated/deleted by the transaction can not be rollbacked back because
they are not there anymore?
--
Rafael Martinez, <r.m.guerrero@usit.uio.no>
Center for Information Technology Services
University of Oslo, Norway
PGP Public Key: http://folk.uio.no/rafael/
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To: pgsql-performance@postgresql.org
Cc: r.m.guerrero@usit.uio.no, heikki@enterprisedb.com
Subject: Re: Need to run CLUSTER to keep performance
In-Reply-To: <47396527.5090801@usit.uio.no>
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