Re: Optimizer problem in 8.1.6 - Mailing list pgsql-general

From Tom Lane
Subject Re: Optimizer problem in 8.1.6
Date
Msg-id 24598.1182534896@sss.pgh.pa.us
Whole thread Raw
In response to Re: Optimizer problem in 8.1.6  (Fernando Schapachnik <fernando@mecon.gov.ar>)
List pgsql-general
Fernando Schapachnik <fernando@mecon.gov.ar> writes:
> En un mensaje anterior, Tom Lane escribi�:
>> Is this query really what you want to do?  Because the OR overrides all
>> the join conditions, meaning that rows having p.id_cola_por_ambito=1
>> AND p.id_situacion!=6 must produce Cartesian products against every
>> row in each of the other tables.

> Yes, yes, we found this while working on improving the query. I just
> wanted to point out that the optimizer was doing a sequential scan
> in a situation it could unfould de active_users definition, add the
> login='xxx' clause, and use the index on the users table.

What for, when the query requires fetching the entire table anyway?

            regards, tom lane

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