Pavel Stehule wrote: > I like a strategy based on risks. Probably there are situation, when the > generic plan is great every > time - INSERTs, UPDATEs via PK, simple SELECTs via PK. generic plan can be > well if almost all data has > similar probability. Elsewhere on bigger data, the probability of pretty slow > plan is higher, and then > we should to prefer custom plan. > > so the strategy - if cost of generic plan is less than some MAGIC CONSTANT > (can be specified by GUC), > then use generic plan. Elsewhere use a custom plan everytime. > > It allow to controll the plan reusing. When MAGIC CONSTANT = 0 .. use custom > plan everytime, When > MAGIC CONSTANT = M, then use generic plan always.
I have a different idea: What about a GUC "custom_plan_threshold" that controls after how many executions a generic plan will be considered, with a default value of 5. A value of -1 could disable generic plans. Yours, Laurenz Albe -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers