Re: MAP syntax for arrays

On 5/8/18 10:18, Alvaro Herrera wrote:
> Peter Eisentraut wrote:
>> On 5/8/18 09:19, Chapman Flack wrote:
>>> On 05/08/2018 08:57 AM, Ildar Musin wrote:
>>>>
>>>> select map (pow(2, x) - 1 for x in array[1,2,3,4,5]);
>>>
>>> I wonder how efficient an implementation would be possible strictly
>>> as a function, without grammar changes?
>>
>> Yeah, you can pass a function to another function (using regprocedure or
>> just oid), so this should be possible entirely in user space.
> 
> How would you invoke it?  It seems you'd be forced to use EXECUTE in a
> plpgsql function, or a C function.

Yes, I was thinking about a C function.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
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