On Wed, Nov 25, 2009 at 7:27 AM, Richard Neill <rn...@cam.ac.uk> wrote: > Sergey Aleynikov wrote: >> >> Hello, >> >>> * Is there any way I can nail the query planner to a particular query >>> plan, >>> rather than have it keep changing its mind? >> >> All these setting leads to choosing different plans. If you have small >> number of complex sensitive queires, you can run explain on them with >> correct settings, then re-order query (joins, subselects) according to >> given query plan, and, before running it, call >> >> set local join_collapse_limit = 1; >> set local from_collapse_limit = 1; > > It's a simple query, but using a complex view. So I can't really re-order > it.
Almost all queries can be reordered to some degree, but you might have to inline the view into the main query to actually be able to do it. Forcing a particular query plan in the manner described here is generally sort of a last resort, though. Usually you want to figure out how to tune things so that the query planner picks the right plan by itself - that's sort of the point of having a query planner... ...Robert -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
