Re: Should array_length() Return NULL

"David E. Wheeler" <david@justatheory.com> writes:
> This surprised me:

>     david=# select array_length('{}'::text[], 1);
>      array_length 
>     --------------
>            [null]

> I had expecte dit to retur 0. I might expect NULL for a NULL param, but not one that's defined but has no elements.

The thing is that that syntax creates an array of zero dimensions,
not one that has 1 dimension and zero elements.  So "0" would be
incorrect.

Our handling of empty arrays leaves something to be desired, I agree,
but making it more consistent seems like a large task.  Hacking
array_length in isolation will certainly not help.
        regards, tom lane