On Sat, Nov 3, 2012 at 10:23 PM, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: > Josh Berkus <josh@xxxxxxxxxxxx> writes: >>> Funny thing is, if I set constraint_exclusion=on, it works as >>> expected. But not with constraint_exclusion=partition. > >> The difference between "on" and "partition" is how it treats UNION. >> This seems to be working as designed. > > Well, what "partition" actually means is "only bother to try constraint > exclusion proofs on appendrel members". UNION ALL trees will get > flattened into appendrels in some cases. In a quick look at the code, > it seems like in recent releases the restrictions are basically that the > UNION ALL arms have to (1) each be a plain SELECT from a single table > with no WHERE restriction; (2) all produce the same column datatypes; > and (3) not have any volatile functions in the SELECT lists. I might be > missing something relevant to the OP's case, but it's hard to tell > without a concrete example. I would think our view succeeds all those tests, but I'm not entirely sure about 2. It does use coalesce too, but I really doubt coalesce is volatile... right? I don't have access to the code during the weekend, but I'll check first thing tomorrow whether we have some datatype inconsistencies I didn't notice. Thanks for the hint. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
