Re: unnesting multirange data types

On 6/9/21 3:44 PM, Jonathan S. Katz wrote:
> On 6/9/21 3:25 PM, Tom Lane wrote:
>> "Jonathan S. Katz" <jkatz(at)postgresql(dot)org> writes:
>>> I would like to decompose the returned multirange into its individual
>>> ranges, similarly to how I would "unnest" an array:
>>
>> +1 for adding such a feature, but I suppose it's too late for v14.
>
> Well, the case I would make for v14 is that, as of right now, the onus
> is on the driver writers / application developers to be able to unpack
> the multiranges.
>
> I haven't tried manipulating a multirange in a PL like Python, maybe
> some exploration there would unveil more or less pain, or if it could be
> iterated over in PL/pgSQL (I'm suspecting no).

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.

In PL/Python, both range types and multirange types are treated as
strings. From there, you can at least ultimately parse and manipulate it
into your preferred Python types, but this goes back to my earlier point
about putting the onus on the developer to do so.

Thanks,

Jonathan