Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3

From:
Subject: Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3
Date: ,
Msg-id: 45F6C75A.4070407@leroymerlin.fr
(view: Whole thread, Raw)
In response to: Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3  (Tom Lane)
List: pgsql-performance

Tree view

Execution plan changed after upgrade from 7.3.9 to 8.2.3  (<>, )
 Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3  (Michael Fuhr, )
  Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3  (<>, )
   Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3  (Richard Huxton, )
    Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3  (<>, )
     Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3  ("Dave Dutcher", )
      Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3  (<>, )
       Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3  ("Dave Dutcher", )
     Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3  (Richard Huxton, )
   Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3  (Alvaro Herrera, )
    Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3  (<>, )
     Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3  (Alvaro Herrera, )
      Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3  (<>, )
       Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3  (Tom Lane, )
        Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3  (<>, )

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:
> <> 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'internetne permettant pas d'assurer l'intégrité de ce message, le contenu de ce message ne représente en aucun cas un
engagementde la part de Leroy Merlin. 



pgsql-performance by date:

From: Cosimo Streppone
Date:
Subject: Re: PostgreSQL in virtual machine
From: "Anton Melser"
Date:
Subject: Re: PostgreSQL 8.2.3 VACUUM Timings/Performance