| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "David E(dot) Wheeler" <david(at)justatheory(dot)com> |
| Cc: | "pgsql-hackers(at)postgresql(dot)org Hackers" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Should array_length() Return NULL |
| Date: | 2013-03-15 22:07:17 |
| Message-ID: | 413.1363385237@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
"David E. Wheeler" <david(at)justatheory(dot)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
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