Re: ARRAY_LENGTH() function behavior with empty array

Understood, and backwards compatibility also of course. Thank you

On Fri, Dec 2, 2016 at 7:20 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> otar shavadze <oshavadze(at)gmail(dot)com> writes:
> > SELECT ARRAY_LENGTH('{}'::INT[], 1)
> > This returns NULL, not so "dangerous" either way, not would be more
> > logically, if array length function will return 0 from empty array,
> > instead of NULL ?
>
> Well, the issue is that you're asking about dimension 1 of a
> zero-dimensional array, so the answer is indeed undefined, not 0.
>
> A lot of people are not terribly happy with PG's array handling,
> but there's enough interconnectedness to the behaviors that it's
> hard to change just one thing ... and there's also backwards
> compatibility to worry about.
>
> regards, tom lane
>