Re: unnesting multirange data types - Mailing list pgsql-hackers

On 6/9/21 4:56 PM, Alvaro Herrera wrote:
> On 2021-Jun-09, Jonathan S. Katz wrote:
>
>> I did a couple more tests around this.
>>
>> As suspected, in PL/pgSQL, there is no way to unpack or iterate over a
>> multirange type.
>
> Uh.  This is disappointing; the need for some way to unnest or unpack a
> multirange was mentioned multiple times in the range_agg thread.  I had
> assumed that there was some way to cast the multirange to a range array,
> or somehow convert it, but apparently that doesn't work.

Just to be pedantic with examples:

  SELECT datemultirange(
    daterange(current_date, current_date + 2),
    daterange(current_date + 5, current_date + 7))::daterange[];

  ERROR:  cannot cast type datemultirange to daterange[]
  LINE 1: ...2), daterange(current_date + 5, current_date + 7))::daterang...

IF there was an array to cast it into an array, we could then use the
array looping construct in PL/pgSQL, but if we could only choose one, I
think it'd be more natural/less verbose to have an "unnest".

> If the supporting pieces are mostly there, then I opine we should add
> something.

Agreed.

Jonathan