Hello.

Is this a bug?

So, if I use the max() aggregate, I receive one row with the value NULL. Is
that correct?

My background is the language plpgsql:

I expected to test for the existance of a maximum with
(...)
SELECT INTO e
max( y ) AS x FROM (table) WHERE (condition);

IF NOT FOUND THEN RETURN; END IF;
(...)

But I have to test with:

(...)
SELECT INTO e
max( y ) AS x FROM (table) WHERE (condition);

IF e.x IS NULL THEN RETURN; END IF;
(...)

Thanks in advance,
Wilhelm

---------------------------(end of broadcast)---------------------------
TIP 7: don't forget to increase your free space map settings

wilhelm.pakulla (AT) gmx (DOT) de writes:
Yup, that's what the SQL spec says to do, and it seems reasonable to me.

IIRC, the spec also says that SUM() over no rows returns NULL, which is
less reasonable --- I'd have defined it as returning zero, myself.
But when in doubt we follow the spec.

regards, tom lane

---------------------------(end of broadcast)---------------------------
TIP 8: explain analyze is your friend