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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2011-10-08 10:41:17 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2011-10-08 10:41:17 -0400 |
| commit | b324384f6bd5d661efeddb83d7f607781e96947d (patch) | |
| tree | 03db550fb66922bff4d83d1cdb08e792a7793ab0 /src | |
| parent | 1ef60dab7049ffac52dee60b5788b6c7bc1f9d67 (diff) | |
| download | postgresql-b324384f6bd5d661efeddb83d7f607781e96947d.tar.gz postgresql-b324384f6bd5d661efeddb83d7f607781e96947d.zip | |
Fix brain fade in cost estimation for index-only scans.
visibility_fraction should not be applied to regular indexscans.
Noted by Cédric Villemain.
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/optimizer/path/costsize.c | 13 |
1 files 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) |