Re: Range types

Dimitri Fontaine <dfontaine@hi-media.com> writes:
> Tom Lane <tgl@sss.pgh.pa.us> writes:
>> Hm, how would you do it with LATERAL?  The problem is not so much
>> composition as the need for a variable number of rounds of
>> composition.

> Let's have a try at it:

> select p2_member, array_accum(p1)
>   from unnest(p2) as p2_member
>        lateral (select period_except(p1_member, p2_member)
>                   from unnest(p1) p1_member) as x(p1);

I don't think that does it.  Maybe I misunderstand LATERAL, but what
that looks like to me is that each p1 will be separately filtered by
each p2, giving rise to a distinct element in the output.  What we
need is for each p1 to be filtered by *all* p2's, successively
(though in any order).
        regards, tom lane