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| author | David Rowley <drowley@postgresql.org> | 2023-08-04 10:47:54 +1200 |
|---|---|---|
| committer | David Rowley <drowley@postgresql.org> | 2023-08-04 10:47:54 +1200 |
| commit | 3fd19a9b23c2906da52f3f3732dbc533477f284d (patch) | |
| tree | 8c78e2d9a14efbb8a0048424c4387baf345ef662 /src/backend/optimizer/path/costsize.c | |
| parent | 3900a02c97c7cc0e211578dc733cff0f4a2b2213 (diff) | |
| download | postgresql-3fd19a9b23c2906da52f3f3732dbc533477f284d.tar.gz postgresql-3fd19a9b23c2906da52f3f3732dbc533477f284d.zip | |
Minor adjustments to WindowAgg startup cost code
This is a follow-on of 3900a02c9 containing some changes which I forgot
to commit locally before forming a patch with git format-patch.
Discussion: https://postgr.es/m/CAApHDvrB0S5BMv+0-wTTqWFE-BJ0noWqTnDu9QQfjZ2VSpLv_g@mail.gmail.com
Diffstat (limited to 'src/backend/optimizer/path/costsize.c')
| -rw-r--r-- | src/backend/optimizer/path/costsize.c | 16 |
1 files changed, 5 insertions, 11 deletions
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c index 8b797e3b462..d6ceafd51c5 100644 --- a/src/backend/optimizer/path/costsize.c +++ b/src/backend/optimizer/path/costsize.c @@ -2933,8 +2933,8 @@ get_windowclause_startup_tuples(PlannerInfo *root, WindowClause *wc, * NULLs are not allowed, but currently, there's no code to * error out if there's a NULL Const. We'll only discover * this during execution. For now, just pretend everything is - * fine and assume that just the current row/range/group will - * be needed. + * fine and assume that just the first row/range/group will be + * needed. */ end_offset_value = 1.0; } @@ -3056,15 +3056,6 @@ cost_windowagg(Path *path, PlannerInfo *root, total_cost = input_total_cost; /* - * Estimate how many tuples we'll need to read from the subnode before we - * can output the first WindowAgg row. - */ - startup_tuples = get_windowclause_startup_tuples(root, winclause, - input_tuples); - - elog(DEBUG1, "startup_tuples = %g", startup_tuples); /* XXX not for commit */ - - /* * Window functions are assumed to cost their stated execution cost, plus * the cost of evaluating their input expressions, per tuple. Since they * may in fact evaluate their inputs at multiple rows during each cycle, @@ -3124,6 +3115,9 @@ cost_windowagg(Path *path, PlannerInfo *root, * cost of the subnode, so we only need to do this when the estimated * startup tuples is above 1.0. */ + startup_tuples = get_windowclause_startup_tuples(root, winclause, + input_tuples); + if (startup_tuples > 1.0) path->startup_cost += (total_cost - startup_cost) / input_tuples * (startup_tuples - 1.0); |