Re: Custom function in where clause

On 10 July 2012 18:36, Pena Kupen <kupen(at)wippies(dot)fi> wrote:
> Hi,
>
> I have searched solution to my problem a few days. On my query, there is big
> performance problem.
> It seems to me, that problem is on where-part of sql and it's function.
>

> How should I handle this situation and use function?
>

I would start by rewriting your function in plain SQL rather than
PL/pgSQL. As a general rule, don't write a function in PL/pgSQL
unless you really need procedurality. This function does not.

For example:

CREATE OR REPLACE FUNCTION get_level_value(_user integer, _id, _area)
RETURNS integer
AS $$
-- Return 3 if there are matching records in table_o, otherwise return 1.
SELECT CASE WHEN EXISTS (
SELECT id
FROM table_o
WHERE userid=_user AND
id=_id AND
area=_area
) THEN 3 ELSE 1 END;
$$
LANGUAGE sql STABLE;

Cheers,
BJ