Message-ID: <4F7D90C0.3090800@gmail.com>
Date: Thu, 05 Apr 2012 14:32:00 +0200
From: Mario Dankoor <m.p.dankoor@gmail.com>
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To: pgsql-sql@postgresql.org
Subject: Re: bad plan
References: <4F7D843E.4060304@ulb.ac.be> <4F7D89F5.7090301@gmail.com>
	<4F7D8B3F.1030402@ulb.ac.be>
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Julien,

I generally try avoid NOT predicates.
If your geo_id is an integer,  try geo_id > -1
or if it's a varchar geo_id > ''.
The idea is that geo_id > 0 is false for null values.

I don't think query optimizers are fond of NOT predicates.

SELECT  t_geo.frequence
        ,ST_SetSRID(gc.geom, 4326) as geom
FROM (
        SELECT  geo_id
               ,count(*) AS frequence
        FROM hit.context_to_context_links
        WHERE geo_id > -1
        AND taxon_id= ANY (
                           SELECT taxon_id
                           FROM rab.ancestors
                           WHERE ancestors.subphylum_id = 18830
                         ) GROUP BY geo_id
      ) as t_geo
JOIN  hit.geo_candidates gc
ON gc.id = t_geo.geo_id;


On 2012-04-05 2:08 PM, Julien Cigar wrote:
> SELECT
>   t_geo.frequence, ST_SetSRID(gc.geom, 4326) as geom
> FROM (
>   SELECT
>     geo_id , count(*) AS frequence
>   FROM
> hit.context_to_context_links
>   WHERE
>     NOT geo_id IS NULL ANDtaxon_id= ANY (
>       SELECT
>         taxon_id
>       FROM
>         rab.ancestors
>       WHERE
>         ancestors.subphylum_id = 18830
>       ) GROUP BY geo_id
> ) as t_geo
> JOIN
>   hit.geo_candidates gc ON gc.id = t_geo.geo_id;