Hi Robert,
On Tue, Feb 9, 2010 at 17:43, Robert Haas
<robertmhaas@gmail.com> wrote:
On Tue, Feb 9, 2010 at 7:08 AM, Jeroen Vermeulen <
jtv@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.
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).
Cheers,
Bart
