Skip site navigation (1) Skip section navigation (2)

Re: not in(subselect) in 8.4

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Grzegorz Jaśkiewicz <gryzman(at)gmail(dot)com>
Cc: "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: not in(subselect) in 8.4
Date: 2009-02-20 15:33:53
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
=?UTF-8?Q?Grzegorz_Ja=C5=9Bkiewicz?= <gryzman(at)gmail(dot)com> writes:
> I mean query like:
> select id from foo where id not in ( select id from bar);
> into:
> select from foo f left join bar b on where is null;

Postgres does not do that, because they don't mean the same thing ---
the behavior for NULLs in is different.

8.4 does understand that NOT EXISTS is an antijoin, though.

			regards, tom lane

In response to


pgsql-performance by date

Next:From: Grzegorz JaśkiewiczDate: 2009-02-20 15:39:56
Subject: Re: not in(subselect) in 8.4
Previous:From: Matthew WakelingDate: 2009-02-20 15:26:43
Subject: Re: SSD performance

Privacy Policy | About PostgreSQL
Copyright © 1996-2017 The PostgreSQL Global Development Group