Обсуждение: ARRAY_LENGTH() function behavior with empty array
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 ?
This is just IMHO.
otar shavadze <oshavadze@gmail.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
Understood, and backwards compatibility also of course. Thank you
On Fri, Dec 2, 2016 at 7:20 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
otar shavadze <oshavadze@gmail.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