Re: array_length(anyarray)

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От Marko Tiikkaja
Тема Re: array_length(anyarray)
Дата
Msg-id 52CED78B.3050703@joh.to
обсуждение исходный текст
Ответ на Re: array_length(anyarray)  (Florian Pflug <fgp@phlo.org>)
Ответы Re: array_length(anyarray)  (Jim Nasby <jim@nasby.net>)
Re: array_length(anyarray)  (Merlin Moncure <mmoncure@gmail.com>)
Список pgsql-hackers
On 1/9/14 5:44 PM, Florian Pflug wrote:
> On Jan9, 2014, at 14:57 , Dean Rasheed <dean.a.rasheed@gmail.com> wrote:
>> On 19 December 2013 08:05, Pavel Stehule <pavel.stehule@gmail.com> wrote:
>>> length should be irrelevant to fact so array starts from 1, 0 or anything
>>> else
>>
>> Yes, this should just return the number of elements, and 0 for an empty array.
>
> +1. Anything that complains about arrays whose lower bound isn't 1 really
> needs a *way* less generic name than array_length().

Problem is, if you're operating on an array which could have a lower 
bound that isn't 1, why would you look at the length in the first place?  You can't access any elements by index, you'd
needto look at 
 
array_lower().  You can't iterate over the array by index, you'd need to 
do  array_lower() .. array_lower() + array_length(), which doesn't make 
sense.  And then there's the myriad of stuff you can do with unnest() 
without actually having to look at the length.  Same goes for 
multi-dimensional arrays: you have even less things you can do there 
with only a length.

So if we give up these constraints, we also make this function 
completely useless.


Regards,
Marko Tiikkaja



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