Re: Need to run CLUSTER to keep performance

From: Rafael Martinez <r(dot)m(dot)guerrero(at)usit(dot)uio(dot)no>
To: Heikki Linnakangas <heikki(at)enterprisedb(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Need to run CLUSTER to keep performance
Date: 2007-11-13 09:03:19
Message-ID: 47396857.1050801@usit.uio.no
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Rafael Martinez wrote:
> Heikki Linnakangas wrote:
>
>> 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?
>

Stupid question, I could have checked this myself. CLUSTER will wait to
be executed until the transaction is finish. I have just checked this.

--
Rafael Martinez, <r(dot)m(dot)guerrero(at)usit(dot)uio(dot)no>
Center for Information Technology Services
University of Oslo, Norway

PGP Public Key: http://folk.uio.no/rafael/

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