Re: MAP syntax for arrays - Mailing list pgsql-hackers

From Peter Eisentraut
Subject Re: MAP syntax for arrays
Date
Msg-id 42cf8743-971d-b816-bd24-c17d70167ebf@2ndquadrant.com
Whole thread Raw
In response to Re: MAP syntax for arrays  (Chapman Flack <chap@anastigmatix.net>)
Responses Re: MAP syntax for arrays  (Alvaro Herrera <alvherre@2ndquadrant.com>)
Re: MAP syntax for arrays  (Ildar Musin <i.musin@postgrespro.ru>)
List pgsql-hackers
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.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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