Re: ARRAY() returning NULL instead of ARRAY[] resp. {}

В Втр, 24/05/2005 в 00:06 -0400, Tom Lane пишет:
> Joe Conway <mail(at)joeconway(dot)com> writes:
> > Markus Bertheau wrote:
> >> why does SELECT ARRAY(SELECT 1 WHERE FALSE) return NULL instead of
> >> ARRAY[] resp. '{}'?
>
> > Why would you expect an empty array instead of a NULL?
>
> I think he's got a good point, actually. We document the ARRAY-with-
> parens-around-a-SELECT syntax as
>
> The resulting one-dimensional array will have an element for
> each row in the subquery result, with an element type matching
> that of the subquery's output column.
>
> To me, that implies that a subquery result of no rows generates a
> one-dimensional array of no elements, not a null array.

By analogy, array_upper('{}'::TEXT[], 1) should return 0 instead of
NULL.

Markus

--
Markus Bertheau ☭ <twanger(at)bluetwanger(dot)de>