Dimitri Fontaine <[email protected]> writes:
> Tom Lane <[email protected]> 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
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