diff options
Diffstat (limited to 'src/backend/optimizer')
| -rw-r--r-- | src/backend/optimizer/path/allpaths.c | 18 | ||||
| -rw-r--r-- | src/backend/optimizer/plan/planner.c | 8 |
2 files changed, 24 insertions, 2 deletions
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index b5bc9b602e2..df3453f99f0 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -1371,9 +1371,23 @@ add_paths_to_append_rel(PlannerInfo *root, RelOptInfo *rel, */ if (rel->consider_startup && childrel->cheapest_startup_path != NULL) { + Path *cheapest_path; + + /* + * With an indication of how many tuples the query should provide, + * the optimizer tries to choose the path optimal for that + * specific number of tuples. + */ + if (root->tuple_fraction > 0.0) + cheapest_path = + get_cheapest_fractional_path(childrel, + root->tuple_fraction); + else + cheapest_path = childrel->cheapest_startup_path; + /* cheapest_startup_path must not be a parameterized path. */ - Assert(childrel->cheapest_startup_path->param_info == NULL); - accumulate_append_subpath(childrel->cheapest_startup_path, + Assert(cheapest_path->param_info == NULL); + accumulate_append_subpath(cheapest_path, &startup_subpaths, NULL); } diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c index 36ee6dd43de..014e80c30e6 100644 --- a/src/backend/optimizer/plan/planner.c +++ b/src/backend/optimizer/plan/planner.c @@ -6414,6 +6414,11 @@ make_sort_input_target(PlannerInfo *root, * Find the cheapest path for retrieving a specified fraction of all * the tuples expected to be returned by the given relation. * + * Do not consider parameterized paths. If the caller needs a path for upper + * rel, it can't have parameterized paths. If the caller needs an append + * subpath, it could become limited by the treatment of similar + * parameterization of all the subpaths. + * * We interpret tuple_fraction the same way as grouping_planner. * * We assume set_cheapest() has been run on the given rel. @@ -6436,6 +6441,9 @@ get_cheapest_fractional_path(RelOptInfo *rel, double tuple_fraction) { Path *path = (Path *) lfirst(l); + if (path->param_info) + continue; + if (path == rel->cheapest_total_path || compare_fractional_path_costs(best_path, path, tuple_fraction) <= 0) continue; |