diff options
| -rw-r--r-- | src/backend/optimizer/path/costsize.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c index 2a49639f125..e42895dc31c 100644 --- a/src/backend/optimizer/path/costsize.c +++ b/src/backend/optimizer/path/costsize.c @@ -1577,8 +1577,7 @@ cost_sort(Path *path, PlannerInfo *root, * at any given instant holds the next tuple from each stream. If there * are N streams, we need about N*log2(N) tuple comparisons to construct * the heap at startup, and then for each output tuple, about log2(N) - * comparisons to delete the top heap entry and another log2(N) comparisons - * to insert its successor from the same stream. + * comparisons to replace the top entry. * * (The effective value of N will drop once some of the input streams are * exhausted, but it seems unlikely to be worth trying to account for that.) @@ -1619,7 +1618,7 @@ cost_merge_append(Path *path, PlannerInfo *root, startup_cost += comparison_cost * N * logN; /* Per-tuple heap maintenance cost */ - run_cost += tuples * comparison_cost * 2.0 * logN; + run_cost += tuples * comparison_cost * logN; /* * Also charge a small amount (arbitrarily set equal to operator cost) per |