"Claudio Lapidus" <clapidus(at)hotmail(dot)com> writes:
> Hello
>
> I would like to know how can I define/create a new aggregate function. I
> need a custom function that operate on a set of text strings and return a
> certain string aggregate based on certain rules. But I cannot figure out how
> can I define such a data set to operate on.
Is this example helpful?
create function concat_agg_accum(varchar, varchar) returns varchar
as 'select $1 || '', '' || $2'
language sql
strict immutable;
create aggregate concat_agg (
basetype = varchar,
stype = varchar,
sfunc = concat_agg_accum
);
--
greg