Re: array_length()

2008/11/5 Peter Eisentraut <peter_e@gmx.net>:
> Pavel Stehule wrote:
>>
>> Hello
>>
>> 2008/11/5 Peter Eisentraut <peter_e@gmx.net>:
>>>
>>> Decibel! wrote:
>>>>
>>>> ISTM it'd be useful to have an array_length function (since I just wrote
>>>> one for work ;), so here's a patch. Note that I don't have the docs
>>>> toolchain setup, so I wasn't able to test the doc patches.
>>>
>>> There is a tiny problem with this implementation: It returns null for an
>>> empty array, not zero.  This is because array_lower and/or array_upper
>>> return null for an empty array, which makes sense for those cases.  We
>>> could
>>> fix this by putting a coalesce around the expression, but since the array
>>> functions return null for all kinds of error cases, this might mask other
>>> problems.  Or we move to a C implementation.
>>>
>>
>> we should to write function isempty(anyarray), that returns true when
>> param is empty.
>
> Well, isn't isempty() just a special case of array_length()?  One or the
> other needs to be implemented, so we might as well go for the general case,
> IMO.
>

sure, but I believe so 90% of using array_length will be test of emty array.

Pavel