2010/10/7 Tom Lane <t...@sss.pgh.pa.us>: > Heikki Linnakangas <heikki.linnakan...@enterprisedb.com> writes: >> On 07.10.2010 10:41, Simon Riggs wrote: >>> Constraint exclusion is linear with respect to number of partitions. >>> Why do you say exponential? > >> For some reason I thought the planner needs to check the constraints of >> the partitions against each other, but you're right, clearly that's not >> the case. Linear it is. > > Well, it's really more like O(mn) where m is the number of partitions > and n is the number of clauses in the query --- and not only that, but > the O() notation is hiding a depressingly high constant factor. And > then there are practical problems like failing to exclude partitions as > soon as there are any parameters in the query.
Does the same considerations apply to partial indexes? I mean, I can replace table partitioning with index partitioning concept. (Well I know it's not really the same). Would then it be the same O(nm) to let the planner choose the right indexes given a certain query? > There's basically no way that we're going to get decent performance for > large numbers of partitions as long as we have to resort to > theorem-proving to lead us to the correct partition. > > regards, tom lane > I'm not sure about MySQL, but Oracle can handle large partitioning. So I would say there's a way to achieve the same goal. -- Vincenzo Romano at NotOrAnd Information Technologies Software Hardware Networking Training Support Security -- cel +393398083886 fix +390823454163 fax +3902700506964 gtalk. vincenzo.rom...@notorand.it skype. notorand.it -- NON QVIETIS MARIBVS NAVTA PERITVS -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers