Re: totally different plan when using partitions - Mailing list pgsql-general

From Alvaro Herrera
Subject Re: totally different plan when using partitions
Date
Msg-id 20090813141640.GC5909@alvh.no-ip.org
Whole thread Raw
In response to totally different plan when using partitions  (Scara Maccai <m_lists@yahoo.it>)
Responses Re: totally different plan when using partitions
List pgsql-general
Scara Maccai wrote:

> explain analyze
>     select nome1,
>     thv3tralacc,
>     dltbfpgpdch
>     FROM cell_bsc_60_0610 as cell_bsc
>         left outer join teststscell73_0610_1 as data on data.ne_id=cell_bsc.nome1
>         left outer join teststscell13_0610_1 as data1 on data1.ne_id=cell_bsc.nome1 and data1.time=data.time
>     where
>
>     data.time >=cell_bsc.starttime and data.time <=cell_bsc.endtime and
>      data.time between '2006-10-01 00:00:00' and '2006-10-06 00:00:00'
> and    data1.time >=cell_bsc.starttime and data1.time <=cell_bsc.endtime
>      and    data1.time between '2006-10-01 00:00:00' and '2006-10-06 00:00:00'
>     and cell_bsc.nome2=2
>
> explain analyze:
>
> http://explain-analyze.info/query_plans/3805-query-plan-2509
>
>
> same query, but using postgresql's partition pruning ("2"):
>
> explain analyze
>     select nome1,
>     thv3tralacc,
>     dltbfpgpdch
>     FROM cell_bsc_60_0610 as cell_bsc
>         left outer join teststscell73 as data on data.ne_id=cell_bsc.nome1
>         left outer join teststscell13 as data1 on data1.ne_id=cell_bsc.nome1 and data1.time=data.time
>     where
>
>     data.time >=cell_bsc.starttime and data.time <=cell_bsc.endtime and
>      data.time between '2006-10-01 00:00:00' and '2006-10-06 00:00:00'
> and    data1.time >=cell_bsc.starttime and data1.time <=cell_bsc.endtime
>      and    data1.time between '2006-10-01 00:00:00' and '2006-10-06 00:00:00'
>     and cell_bsc.nome2=2

Huh, clearly not the same query (you're using the partition directly in
the first query) ...  Doing two changes at once is not helping your
case.

--
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

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