Re: 'alternatives' - Mailing list pgsql-general

From Andres Freund
Subject Re: 'alternatives'
Date
Msg-id 20121128223238.GC616@awork2.anarazel.de
Whole thread Raw
In response to Re: 'alternatives'  (Christophe Pettus <xof@thebuild.com>)
Responses Re: 'alternatives'
List pgsql-general
Hi,

On 2012-11-28 14:16:18 -0800, Christophe Pettus wrote:
> Thanks!

Not much to thank for, the answer was actually wrong...

> Does that apply to views as well?  (This particular plan was not from a prepared or PL/pgSQL statement, but did
includeviews.) 

Its not really relevant for views no.

The real answer for this is that this actually a 8.4 feature not the
aforementioned 9.2 feature.

The commit introducing this is:
http://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=bd3daddaf232d95b0c9ba6f99b0170a0147dd8af

What that does to add hashing support for IN(). But hashing can be
pessimal in comparison to a explicit check if only a few values come in,
so this can be checked at runtime after the above commit...

Greetings,

Andres Freund


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