"Pavel Stehule" <pavel(dot)stehule(at)gmail(dot)com> writes:
> postgres=# create function simplefce(a int, b int) returns int as
> $$select $1 + $2$$ language sql immutable strict;
> CREATE FUNCTION
> postgres=# create function simplefce1(a int, b int) returns int as
> $$begin return a+b; end;$$ language plpgsql immutable strict;
> CREATE FUNCTION
That's a pretty unfair comparison, because that SQL function is simple
enough to be inlined. The place to use plpgsql is when you need some
procedural logic; at which point a SQL function simply fails to provide
the required functionality.
regards, tom lane