Re: Convert a text list to text array? Was: Denormalizing during

Guy Fraser wrote:
> The email at the bottom gave me an idea, but it doesn't quite work:
>
> CREATE AGGREGATE accumulate(
> BASETYPE = text,
> SFUNC = textcat,
> STYPE = text,
> INITCOND = '' );
> --
> SELECT ('{' || ltrim(accumulate(',' || tablename),',') || '}') as cruft
> FROM pg_tables
> WHERE hasindexes = 'f';
>
> cruft
> ---------------------------
> {pg_xactlock,pg_listener}
> (1 row)
>
> This produces somthing that looks like it could be able to be converted
> into an array but I cant figure out how to make it work.
>

If I understand correctly, the function array_accum() distributed with
PL/R can do exactly what you're looking for (you need the function, but
you don't necessarily need to use PL/R):

CREATE OR REPLACE FUNCTION array_accum (_name, name)
RETURNS name[]
AS '$libdir/plr','array_accum'
LANGUAGE 'C';

CREATE AGGREGATE accumulate (
sfunc = array_accum,
basetype = name,
stype = _name
);

regression=# SELECT accumulate(tablename) as cruft FROM pg_tables WHERE
tablename LIKE 'c%';
cruft
---------------------------------------
{connectby_int,connectby_text,ct,cth}
(1 row)

See:
http://www.joeconway.com/plr/doc/plr-aggregate-funcs.html
and download at:
http://www.joeconway.com/plr/

HTH,

Joe