diff options
Diffstat (limited to 'src/backend/optimizer/path')
| -rw-r--r-- | src/backend/optimizer/path/allpaths.c | 18 |
1 files changed, 16 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); } |