On Thu, Nov 20, 2008 at 4:11 PM, Tom Lane <[EMAIL PROTECTED]> wrote: > "Robert Haas" <[EMAIL PROTECTED]> writes: >> It looks to me like section 34.10 of the docs might benefit from some >> sort of update in light of this patch, since the builtin array_agg now >> does the same thing as the proposed user-defined array_accum, only >> better. Presumably we should either pick a different example, or add >> a note that a builtin is available that does the same thing more >> efficiently. > > I did the latter. If you can think of an equally plausible and short > example of a polymorphic aggregate, we could certainly replace the > example instead ...
maybe show how to stack arrays? see: http://www.nabble.com/text-array-accumulate-to-multidimensional-text-array-td20098591.html IMO a good example of how you can write aggregates in a language other than C, which is IMO an underutilized technique. CREATE OR REPLACE FUNCTION array_cat1(p1 anyarray, p2 anyarray) RETURNS anyarray AS $$ SELECT CASE WHEN $1 = '{}'::text[] THEN ARRAY[p2] ELSE ARRAY_CAT(p1, p2) END; $$ LANGUAGE sql; CREATE AGGREGATE array_stack(anyarray) ( sfunc = array_cat1, stype = anyarray, initcond = '{}' ); merlin -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
