On Tue, Oct 20, 2015 at 10:52:05AM -0400, Robert Haas wrote: > On Mon, Oct 19, 2015 at 8:02 PM, Jim Nasby <jim.na...@bluetreble.com> wrote: > > On 10/19/15 1:07 PM, David Fetter wrote: > >> > >> What I'd like to do is lift the restriction on ROWS FROM(), which > >> currently requires that the stuff inside the parentheses set-returning > >> functions, so constructs something like the following would actually work: > >> > >> SELECT * > >> FROM > >> ROWS FROM ( > >> (VALUES (...), ..., (...)), > >> (SELECT ... ), > >> (INSERT ... RETURNING ... ), > >> my_srf() > >> ) > >> AS t(...) > >> > >> would actually work. > > > > > > There's been a few places where I would have found that handy. > > Why not just use a subquery with UNION ALL?
Because UNION ALL glues the queries vertically, not horizontally. ROWS FROM() turns things like: A() -- 1 2 3 4 5 and B() -- a 10 b 9 c 8 d 7 e 6 f 5 g 4 into ROWS FROM(A(), B()) ------------------- 1 a 10 2 b 9 3 c 8 4 d 7 5 e 6 NULL f 5 NULL g 4 UNION ALL turns combining A() and B() into an error because the output row types don't match. Cheers, David. -- David Fetter <da...@fetter.org> http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fet...@gmail.com Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
