Manfred Koizar <[EMAIL PROTECTED]> writes: > Cutting down the number of heap page fetches if PF1 * L > P and P < > effective_cache_size seems like an obvious improvement, but I was not > able to figure out where to make this change. Maybe it belongs into > costsize.c near > run_cost += outer_path_rows * > (inner_path->total_cost - inner_path->startup_cost) * > joininfactor;
I've been intending for some time to try to restructure the cost estimator so that repeated indexscans can be costed more accurately. Within the context of the heap-fetch-estimating algorithm, I think the entire execution of a nestloop-with-inner-index-scan could probably be treated as a single scan. I'm not sure how we adjust the estimates for the index-access part, though clearly those are too high as well. This doesn't seem to be a localized change unfortunately. Certainly costsize.c can't do it alone. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly