2010/2/11 Bart Samwel <b...@samwel.tk>: > Hi Robert, > > On Tue, Feb 9, 2010 at 17:43, Robert Haas <robertmh...@gmail.com> wrote: >> >> On Tue, Feb 9, 2010 at 7:08 AM, Jeroen Vermeulen <j...@xs4all.nl> wrote: >> > = Projected-cost threshold = >> > >> > If a prepared statement takes parameters, and the generic plan has a >> > high >> > projected cost, re-plan each EXECUTE individually with all its parameter >> > values bound. It may or may not help, but unless the planner is vastly >> > over-pessimistic, re-planning isn't going to dominate execution time for >> > these cases anyway. >> >> How high is high? > > Perhaps this could be based on a (configurable?) ratio of observed planning > time and projected execution time. I mean, if planning it the first time > took 30 ms and projected execution time is 1 ms, then by all means NEVER > re-plan. But if planning the first time took 1 ms and resulted in a > projected execution time of 50 ms, then it's relatively cheap to re-plan > every time (cost increase per execution is 1/50 = 2%), and the potential > gains are much greater (taking a chunk out of 50 ms adds up quickly).
It could be a good idea. I don't belive to sophisticate methods. There can be a very simply solution. The could be a "limit" for price. More expensive queries can be replaned every time when the price will be over limit. Regards Pavel Stehule > > Cheers, > Bart > -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
