Re: Manual vs automatic functionality

> I wouldn't mind being able to provide hints to the planner.  For
> example, I have some set-returning functions that typically return
> 10-100 rows and I usually have a good idea of how many rows a
> particular set of inputs will generate, and sometimes I know other
> characteristics about those rows as well.  But the planner, not
> knowing any better, always assumes the functions will return 1000
> rows, which presumably affects the plan, sometimes for the worse.
> Here's an example of a problem I've had:
> 
> http://archives.postgresql.org/pgsql-performance/2004-08/msg00236.php
> 
> I've wondered if the ability to provide hints about the expected
> output from set-returning functions would be useful.

Hmmm, you could jank that by making a new GUC:

SET expected_srf_rows TO 152;
SELECT * FROM myfunction();

Chris