Ronan Dunklau <rdunklau@xxxxxxxxx> writes: > I'm trying to define a "weighted mean" aggregate using postgresql create > aggregate feature. > I've been able to quickly write the required pgsql code to get it > working, but after testing it on a sample 10000 rows table, it seems to > be approximately 6 to 10 times slower than pure sql. It might help to use a two-element array for the transition state, instead of a custom composite type. > My initial implementation was in pl/pgsql, and did not mark the > functions as immutable. I did so after a suggestion from an irc user, > but it did not change anything performance wise. Those suggestions would possibly help for a function that's meant to be inlined into larger SQL expressions, but they won't do much for an aggregate support function. I'm not real sure, but I think plpgsql might be faster in this context. Another thing to think about is whether you really need type numeric here. float8 would be a lot faster ... though you might have roundoff issues. regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
