Re: Removing Inner Joins

From: Atri Sharma <atri(dot)jiit(at)gmail(dot)com>
To: Antonin Houska <antonin(dot)houska(at)gmail(dot)com>
Cc: Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Removing Inner Joins
Date: 2013-07-10 07:18:54
Message-ID: CAOeZVifR4ba3=j4e+0e03EYzPHPaKXu7yV1DmL4jEyq-Ss9y9w@mail.gmail.com
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> Can you please post an example of such a join removal? I mean a query before
> and after the removal. Thanks,

Courtesy Robert Haas:

SELECT foo.x, foo.y, foo.z FROM foo WHERE foo.x = bar.x

Conditions:

1) foo.x is not null.

2) foo (x) is a foreign key referencing bar (x).

We can ignore bar completely in this case i.e. avoid scanning bar.

Regards,

Atri

--
Regards,

Atri
l'apprenant

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