Date: Sat, 30 Oct 2004 01:07:37 -0500
From: "Jim C. Nasby" <decibel@decibel.org>
To: Michael Fuhr <mike@fuhr.org>
Cc: pgsql-general@postgresql.org, pgsql-docs@postgresql.org
Subject: Re: [GENERAL] Turning a subselect into an array
Message-ID: <20041030060737.GB55164@decibel.org>
References: <20041028223729.GF55164@decibel.org>
	<20041028232152.GA76168@winnie.fuhr.org>
	<20041029221302.GU55164@decibel.org>
	<20041030044056.GA19888@winnie.fuhr.org>
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Thanks again for the help. I did manage to find that after a bunch of
searching in the mailing list. There should really be a portion of the
docs dedicated to array handling.

On Fri, Oct 29, 2004 at 10:40:57PM -0600, Michael Fuhr wrote:
> On Fri, Oct 29, 2004 at 05:13:02PM -0500, Jim C. Nasby wrote:
> > Ok, next stupid question that I can't find in the docs... How would I
> > join a table to an array? IE: if I have an array of primary keys for
> > some table and I want to get the name field from that table and turn it
> > back into an array, how would I do that?
> 
> See the "Subquery Expressions" and "Row and Array Comparisons"
> sections in the PostgreSQL documentation:
> 
> http://www.postgresql.org/docs/7.4/static/functions-subquery.html
> http://www.postgresql.org/docs/7.4/static/functions-comparisons.html
> 
> If I understand you correctly, this should work:
> 
> SELECT ARRAY(SELECT name FROM foo WHERE id = ANY(ARRAY[1,2,3]));
> 
> A test I just ran showed "id = ANY(ARRAY[1,2,3])" doing a sequential
> scan whereas "id IN (1,2,3)" did an index scan, so you might want to
> use the latter if possible.
> 
> -- 
> Michael Fuhr
> http://www.fuhr.org/~mfuhr/
> 
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-- 
Jim C. Nasby, Database Consultant               decibel@decibel.org 
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