From: =?utf-8?q?C=C3=A9dric_Villemain?= <cedric@2ndquadrant.com>
Reply-To: cedric@2ndquadrant.com
Organization: 2ndQuadrant
To: pgsql-performance@postgresql.org
Subject: Re: Performance of a large array access by position (tested version
	9.1.3)
Date: Thu, 28 Jun 2012 12:22:35 +0200
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Cc: Pavel Stehule <pavel.stehule@gmail.com>,
 Marc Mamin <M.Mamin@intershop.de>,
	Jesper Krogh <jesper@krogh.cc>, Maxim Boguk <maxim.boguk@gmail.com>
References: 
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	<C4DAC901169B624F933534A26ED7DF310861B5E9@JENMAIL01.ad.intershop.net>
	<CAFj8pRCddmsCZFJgEG5zqGd5wj3RuhODJKD4SLpdT5gnfdrEGw@mail.gmail.com>
In-Reply-To: 
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> >> >>> Is that behaviour is correct?
> >>=20
> >> yes - access to n position means in postgresql - skip n-1 elements
> >=20
> > Hmmm...
> >=20
> > how many elements to be skipped here ?
>=20
> there are two independent stages:
>=20
> a) detoast - loading and decompression (complete array is detoasted)
> b) access
>=20
> if you has very large arrays, then @a is significant

There is a place to add PG_GETARG_ARRAY_P_SLICE. The code is just not done=
=20
yet.=20

=2D-=20
C=C3=A9dric Villemain +33 (0)6 20 30 22 52
http://2ndQuadrant.fr/
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