"Sergey E. Koposov" <math@sai.msu.ru> writes:
> ... Nothing else and nothing internal need not to be changed to
> insert new two-arg. aggregate functions into the core.
> Am I right in this ?

IIRC the main issues are the syntax of CREATE AGGREGATE and the actual
implementation in nodeAgg.c. See previous discussions, eg
http://archives.postgresql.org/pgsql...3/msg00512.php

I would really prefer to see CREATE AGGREGATE normalized to have a
syntax comparable to CREATE FUNCTION (or DROP AGGREGATE for that
matter):
CREATE AGGREGATE aggname (typname [, ... ]) ...definition...
but it's not clear how to get there without breaking backwards
compatibility :-(

regards, tom lane

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