Re: OUT parameter

Daniel Caune wrote:

> Is there any suggestion against using OUT parameter for local
> calculation such as using a local variable?
>
> CREATE OR REPLACE FUNCTION foo(a IN int,
> b1 OUT int,
> b2 OUT int)
> AS $$
> BEGIN
> FOR (...) LOOP
> b1 = (...);
> b2 = (...);
> END LOOP;
> END;
> $$ LANGUAGE PLPGSQL;

I'd say there's no problem with this, PROVIDED you can ensure you'll never abort before completing the computation. It's not a good idea to modify out parameters partway; programmers (myself included) have this nasty habit of assuming, rightly or wrongly, that a failed function call won't have destroyed the parameters.

If you can't ensure you'll always complete, use locals.

-Owen

> Daniel Caune wrote:
>> Is there any suggestion against using OUT parameter for local
>> calculation such as using a local variable?

In plpgsql (at least in the current implementation) an OUT parameter is
pretty much just a local variable, and so there's no efficiency argument
against using it as a temporary. Whether you consider this good style
is a matter of opinion.

"Owen Jacobson" <ojacobson(at)osl(dot)com> writes:
> I'd say there's no problem with this, PROVIDED you can ensure you'll
> never abort before completing the computation.

Not really an issue in Postgres: we do not support pass-by-reference
parameters and are unlikely to start doing so. There isn't any way
that you can affect locals of a calling procedure before you return.

regards, tom lane