How to check existing aggregate functions in Postgres?

Question

In Postgresql, you can create additional aggregate functions with

CREATE AGGREGATE name(...); 

But this gives an error if the aggregate already exists inside the database, so how can I check if the aggregate exists in the Postgres database?

Answer 1

 SELECT * FROM pg_proc WHERE proname = 'name' AND proisagg; 

• http://www.postgresql.org/docs/8.3/interactive/catalogs-overview.html
• http://www.postgresql.org/docs/8.3/interactive/catalog-pg-aggregate.html
• http://www.postgresql.org/docs/8.3/interactive/catalog-pg-proc.html

Answer 2

 drop aggregate if exists my_agg(varchar); create aggregate my_agg(varchar) (...); select * from pg_aggregate where aggfnoid = 'my_agg'::regproc;