> > Hello, > > Stable and immutable functions do not improve performance when used within > the GROUP BY clause. > Here, the function will be called for each row. > > To avoid it, I can replace the funtion by its arguments within GROUP BY.
Shame on me ! This is of course bullsh... It has nothing to do with immutability and can only applies to few cases e.g: it's fine for select x+1 ... group by x, but not for select x^2 ... group by x Marc Mamin -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
