Re: proposal: searching in array function - array_position

On 3/18/15 12:27 PM, Pavel Stehule wrote:
>> On 3/17/15 8:06 PM, Alvaro Herrera wrote:
>>
>>> My main question regarding this patch is whether the behavior with MD
>>> arrays is useful at all.  Suppose I give it this:
>>>
>>> alvherre=# select array_offset('{{{1,2},{3,4},{5,6}},{{2,3},{4,5},{6,7}}}',
>>> 3);
>>>    array_offset
>>> --------------
>>>               3
>>> (1 fila)
>>>
>>> What can I do with the "3" value it returned?  Certainly not use it as
>>> an offset to get a slice of the original array.  The only thing that
>>> seems sensible to me here is to reject the whole thing with an error,
>>> that is, only accept 1-D arrays here.  We can later extend the function
>>> by allowing higher dimensionality as long as the second argument is an
>>> array one dimension less than the first argument.  But if we allow the
>>> case on its appearance, it's going to be difficult to change the
>>> behavior later.
>>>
> I designed this possibility (use ND arrays)
> mainly for info, if some value exists or not.

Why not use =ANY() for that?

> I am thinking, so this behave is correct (there is no other possible), but
> it is only corner case for this functionality - and if you are thinking, so
> better to disallow it, I am not against. My main focus is 1ND array.

A nonsensical answer for multi-dimensional arrays is worse than no 
answer at all.  I think raising an exception is better.


.m