On Tue, Jan 22, 2013 at 3:46 PM, Andrew Dunstan <and...@dunslane.net> wrote:
> The query is pretty simple and standard, the behaviour (and the plan) is > totally different when it comes to a partitioned table. > >> >> Partioned table query => explain analyze SELECT "sb_logs".* FROM >> "sb_logs" WHERE (device_id = 901 AND date_taken = (SELECT MAX(date_taken) >> FROM sb_logs WHERE device_id = 901)); >> >> > And there you have it. Constraint exclusion does not work in cases like > this. It only works with static expressions (such as a literal date in this > case). Ok, but I would have expected same plant repeated 4 times. When the table is not partitioned, the plan is defintely smarter: it knows that index is reversed and looks for max with an index scan backward). When the table is partitioned, it scan forward and I guess it will always do a full index scan. -- rd This is the way the world ends. Not with a bang, but a whimper.
