Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3

From: <vincent(dot)moreau(at)leroymerlin(dot)fr>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Michael Fuhr <mike(at)fuhr(dot)org>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3
Date: 2007-03-13 15:46:34
Message-ID: 45F6C75A.4070407@leroymerlin.fr
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-performance

Thanks for the advice Tom !

Setting enable_nestloop = off did improve the query a much better way
than setting enable_seqscan to off.

It does not screw the costs either (I had very odd costs with
enable_seqscan to off like this : Nested Loop
(cost=400001665.30..400002197.96 rows=1 width=96)

Is there a "performance risk" to have enable_nestloop = off for other
queries ?

If I had the choice, should I go for index creation for the specific
tables or should I tweak the optimizer with enable_nestloop = off ?

Thanks again to all of you for your help.

Best Regards,
Vincent

Tom Lane wrote:
> <vincent(dot)moreau(at)leroymerlin(dot)fr> writes:
>
>> I was able to improve response time by seting enable_seqscan to off
>>
>
> enable_nestloop = off would probably be a saner choice, at least for
> this particular query.
>
> regards, tom lane
>
> ---------------------------(end of broadcast)---------------------------
> TIP 3: Have you checked our extensive FAQ?
>
> http://www.postgresql.org/docs/faq
>
>

Ce message et toutes les pièces jointes sont établis à l'attention exclusive de leurs destinataires et sont confidentiels. Si vous recevez ce message par erreur, merci de le détruire et d'en avertir immédiatement l'expéditeur. L'internet ne permettant pas d'assurer l'intégrité de ce message, le contenu de ce message ne représente en aucun cas un engagement de la part de Leroy Merlin.

In response to

Browse pgsql-performance by date

  From Date Subject
Next Message Heikki Linnakangas 2007-03-13 15:56:11 Re: Postgres batch write very slow - what to do
Previous Message Tom Lane 2007-03-13 15:29:09 Re: Postgres batch write very slow - what to do