To: Christoph Haller <ch@rodos.fzk.de>
Cc: gsstark@mit.edu (Greg Stark), pgsql-sql@postgresql.org
Subject: Re: Concatenate results of a single column query
References: <200404191315.PAA09557@rodos>
In-Reply-To: <200404191315.PAA09557@rodos>
From: Greg Stark <gsstark@mit.edu>
Organization: The Emacs Conspiracy; member since 1992
Date: 19 Apr 2004 09:45:38 -0400
Message-ID: <87k70c5bel.fsf@stark.xeocode.com>
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Christoph Haller <ch@rodos.fzk.de> writes:

> Interesting feature, but I cannot find function array_append: 
> ERROR:  AggregateCreate: function array_append(integer[], integer) does not exist

It's new in Postgres 7.4

I think you could do this in 7.3 though, it would just be more awkward. Try ||
but I think that's new in 7.4 as well. Otherwise I think you would have to
pick out the upper bound of the array with array_dims and set the upper+1'th
element of the array.

If you're doing text you may want to go directly to a textual concatenation
like:

CREATE FUNCTION concat_agg_accum(text, text) RETURNS text
    AS 'select $1 || '', '' || $2'
    LANGUAGE sql IMMUTABLE STRICT;

CREATE AGGREGATE concat_agg (
    BASETYPE = text,
    SFUNC = concat_agg_accum,
    STYPE = text
);


-- 
greg