From b324384f6bd5d661efeddb83d7f607781e96947d Mon Sep 17 00:00:00 2001 From: Tom Lane <tgl@sss.pgh.pa.us> Date: Sat, 8 Oct 2011 10:41:17 -0400 Subject: [PATCH] Fix brain fade in cost estimation for index-only scans. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit visibility_fraction should not be applied to regular indexscans. Noted by Cédric Villemain. --- src/backend/optimizer/path/costsize.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c index e480797ca8e..45c5524d309 100644 --- a/src/backend/optimizer/path/costsize.c +++ b/src/backend/optimizer/path/costsize.c @@ -264,6 +264,7 @@ cost_index(IndexPath *path, PlannerInfo *root, if (!enable_indexscan) startup_cost += disable_cost; + /* we don't need to check enable_indexonlyscan; indxpath.c does that */ /* * Call index-access-method-specific code to estimate the processing cost @@ -345,7 +346,8 @@ cost_index(IndexPath *path, PlannerInfo *root, (double) index->pages, root); - pages_fetched = ceil(pages_fetched * visibility_fraction); + if (indexonly) + pages_fetched = ceil(pages_fetched * visibility_fraction); max_IO_cost = (pages_fetched * spc_random_page_cost) / num_scans; @@ -366,7 +368,8 @@ cost_index(IndexPath *path, PlannerInfo *root, (double) index->pages, root); - pages_fetched = ceil(pages_fetched * visibility_fraction); + if (indexonly) + pages_fetched = ceil(pages_fetched * visibility_fraction); min_IO_cost = (pages_fetched * spc_random_page_cost) / num_scans; } @@ -381,7 +384,8 @@ cost_index(IndexPath *path, PlannerInfo *root, (double) index->pages, root); - pages_fetched = ceil(pages_fetched * visibility_fraction); + if (indexonly) + pages_fetched = ceil(pages_fetched * visibility_fraction); /* max_IO_cost is for the perfectly uncorrelated case (csquared=0) */ max_IO_cost = pages_fetched * spc_random_page_cost; @@ -389,7 +393,8 @@ cost_index(IndexPath *path, PlannerInfo *root, /* min_IO_cost is for the perfectly correlated case (csquared=1) */ pages_fetched = ceil(indexSelectivity * (double) baserel->pages); - pages_fetched = ceil(pages_fetched * visibility_fraction); + if (indexonly) + pages_fetched = ceil(pages_fetched * visibility_fraction); min_IO_cost = spc_random_page_cost; if (pages_fetched > 1) -- GitLab