Tom Lane wrote:
> C functions have always been able to return sets too; you don't honestly
> think that a SQL function can do something a C function can't, do you?
The original dblink is an example.
>
> There are really two independent improvements here: one is the ability
> for plpgsql functions to return sets, and the other is a group of
> improvements that make it easier to use a function-returning-set,
> independently of what language it's written in.
>
As an example, although you *could* return a composite type before, it
was almost useless, because what you actually got returned to you was a
pointer:
test=# create function get_foo() returns setof foo as 'select * from
foo' language sql;
CREATE
test=# select get_foo(); get_foo
----------- 137867648 137867648 137867648
(3 rows)
In order to get the individual columns, you had to do:
test=# select f1(get_foo()), f2(get_foo()), f3(get_foo()); f1 | f2 | f3
----+----+----- 1 | 1 | abc 1 | 2 | def 2 | 1 | ghi
(3 rows)
Pretty ugly, but it did work.
What about this:
Functions returning multiple rows and/or multiple columns are
now much easier to use than before. You can call such a
"table function" in the SELECT FROM clause, treating its output
like a table. Also, plpgsql functions can now return sets.
Joe