Hello I still thinking about a "median" type functions. My idea is to introduce a new syntax for stype definition - like
stype = type, or stype = ARRAY OF type [ ORDER [ DESC | ASC ]], or stype = TUPLESTORE OF type, or stype = TUPLESORT OF type [ DESC | ASC ] when stype is ARRAY of then final and transistent functions can be a PL functions. When stype isn't scalar, then sfunc can be undefined (it use a buildin functions). Then we can implement a aggregate only with final functions. so median function can be defined: CREATE FUNCTION num_median_final(internal) RETURNS numeric AS ... CREATE AGGREGATE median(numeric) (stype = TUPLESORT OF numeric, finalfunc = num_median_final); This feature has impact primary on agg executor, and can be relative simple - no planner changes (or not big), minimal parser changes. Main reason for this feature is possible access to tuplesort and tuplesort. I hope, so this can solve a problems with computing a median and similar functions on very large datasets. comments? regards -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
