Re: proposal: searching in array function - array_position

2015-01-16 17:57 GMT+01:00 Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>:

> On 1/16/15 3:39 AM, Pavel Stehule wrote:
>
>> I am proposing a simple function, that returns a position of element in
>> array.
>>
>
> Yes please!
>
> FUNCTION array_position(anyarray, anyelement) RETURNS int
>>
>
> That won't work on a multi-dimensional array. Ideally it needs to accept a
> slice or an element and return the specifier for the slice.
>

It is question, what is a result - probably, there can be a
multidimensional variant, where result will be a array

array_position([1,2,3],2) --> 2
array_position([[1,2],[2,3],[3,4]], [2,3]) --> 2 /* 2nd parameter should to
have N-1 dimension of first parameter */
array_position_md([1,2,3],2) --> [2]
array_position_md([[1,2],[2,3],[3,4]], 2) --> [2,1]

another question is how to solve more than one occurrence on one value -
probably two sets of functions - first returns first occurrence of value,
second returns set of occurrence

>
> This wouldn't be so bad if we had an easier way to extract subsets of an
> array, but even that is really ugly because whatever you extract keeps the
> original number of dimensions.
>
> Implementation is simple (plpgsql code)
>>
>
> This would actually be written in C though, yes? Otherwise it's not really
> any better than just doing an extension...
>

Sure, I expect a C implementation

Pavel

> --
> Jim Nasby, Data Architect, Blue Treble Consulting
> Data in Trouble? Get it in Treble! http://BlueTreble.com
>