Robert Haas wrote: > One trick that some system use is avoid replanning as much as we do > by, for example, saving plans in a shared cache and reusing them even > in other sessions. That's hard to do in our architecture because the > controlling GUCs can be different in every session and there's not > even any explicit labeling of which GUCs control planner behavior. But > if you had it, then extra planning cycles would be, perhaps, more > tolerable.
>From my experience with Oracle I would say that that is a can of worms. Perhaps it really brings the performance benefits they claim, but a) there have been a number of bugs where the wrong plan got used (you have to keep several plans for the same statement around, since - as you say - different sessions have different environments) b) it is a frequent problem that this shared memory area grows too large if the application does not use prepared statements but dynamic SQL with varying constants. Yours, Laurenz Albe -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
