Dimitri Fontaine <dfonta...@hi-media.com> writes: > Tom Lane <t...@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 -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers