ssage d'origine-
De : Tom Lane [mailto:[EMAIL PROTECTED]
Envoyé : 6 août 2007 21:31
À : Gregory Stark
Cc : Heikki Linnakangas; Mouhamadou Dia; pgsql-bugs@postgresql.org
Objet : Re: RE : RE : [BUGS] BUG #3519: Postgres takes the wrong query plan
resulting in performance issues
Gregory Sta
[mailto:[EMAIL PROTECTED] De la part de Heikki
> Linnakangas
> Envoyé : 6 août 2007 15:32
> À : Mouhamadou Dia
> Cc : pgsql-bugs@postgresql.org
> Objet : Re: RE : [BUGS] BUG #3519: Postgres takes the wrong query plan
> resulting in performance issues
>
> Mouhamadou Dia
"Tom Lane" <[EMAIL PROTECTED]> writes:
> Gregory Stark <[EMAIL PROTECTED]> writes:
>> The structure of your query is a whole series of left outer joins, the result
>> of which is then (inner) joined with one more table. The outer joins return a
>> whole lot of records but the inner join is only go
Cc : pgsql-bugs@postgresql.org
Objet : Re: RE : [BUGS] BUG #3519: Postgres takes the wrong query plan
resulting in performance issues
Mouhamadou Dia wrote:
> I'm sending in attachment the output of the explain analyze command and the
> create table statements of tables involved in the q
Gregory Stark <[EMAIL PROTECTED]> writes:
> The structure of your query is a whole series of left outer joins, the result
> of which is then (inner) joined with one more table. The outer joins return a
> whole lot of records but the inner join is only going to match a few of them.
Hmmm ... actuall
"Heikki Linnakangas" <[EMAIL PROTECTED]> writes:
> Have you played with enable_seqscan=off or enable_hashjoin=off? That's
> not a good long term solution, but it would be interesting to see what
> happens.
I think this is a case where Postgres just doesn't know it can re-order near
an outer join
07 15:32
> À : Mouhamadou Dia
> Cc : pgsql-bugs@postgresql.org
> Objet : Re: RE : [BUGS] BUG #3519: Postgres takes the wrong query plan
> resulting in performance issues
>
> Mouhamadou Dia wrote:
>> I'm sending in attachment the output of the explain analyze command and
Mouhamadou Dia wrote:
> I'm sending in attachment the output of the explain analyze command and the
> create table statements of tables involved in the query.
Wait, you said that the query takes 20 seconds on 8.2, but the explain
analyze output says that it actually took 50 seconds. Is this the o
