Re: UNNEST ... WITH ORDINALITY (AND POSSIBLY OTHER STUFF)

From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
To: Caleb(dot)Welton <caleb(dot)welton(at)emc(dot)com>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, itagaki(dot)takahiro <itagaki(dot)takahiro(at)gmail(dot)com>, david <david(at)fetter(dot)org>
Subject: Re: UNNEST ... WITH ORDINALITY (AND POSSIBLY OTHER STUFF)
Date: 2010-11-19 19:31:05
Message-ID: 1290194728-sup-123@alvh.no-ip.org
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Excerpts from Caleb.Welton's message of vie nov 19 15:48:06 -0300 2010:
> Note the standard also supports unnesting multiple arrays concurrently, the rule for handling arrays with different lengths is to use null padding of the shorter array.
>
> SELECT * FROM
> UNNEST( ARRAY[5,2,3,4],
> ARRAY['hello', 'world'] )
> WITH ORDINALITY AS t(a,b,i);
>
> a b i
> --- ---------- ------
> 5 'hello' 1
> 2 'world' 2
> 3 3
> 4 4
> (4 rows)

Hmm, this is pretty interesting and useful --- I had to deal with some
XPath code not long ago and I had to turn to plpgsql; I think it could
have been done with multi-array unnest.

--
Álvaro Herrera <alvherre(at)commandprompt(dot)com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

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