diff options
Diffstat (limited to 'src/backend/optimizer/path/allpaths.c')
| -rw-r--r-- | src/backend/optimizer/path/allpaths.c | 21 |
1 files changed, 10 insertions, 11 deletions
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index edba5e49a85..30728be85af 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -2697,20 +2697,19 @@ get_useful_pathkeys_for_relation(PlannerInfo *root, RelOptInfo *rel, EquivalenceClass *pathkey_ec = pathkey->pk_eclass; /* - * We can only build a sort for pathkeys which contain an EC - * member in the current relation's target, so ignore any suffix - * of the list as soon as we find a pathkey without an EC member - * in the relation. + * We can only build a sort for pathkeys that contain a + * safe-to-compute-early EC member computable from the current + * relation's reltarget, so ignore the remainder of the list as + * soon as we find a pathkey without such a member. * - * By still returning the prefix of the pathkeys list that does - * meet criteria of EC membership in the current relation, we - * enable not just an incremental sort on the entirety of - * query_pathkeys but also incremental sort below a JOIN. + * It's still worthwhile to return any prefix of the pathkeys list + * that meets this requirement, as we may be able to do an + * incremental sort. * - * If requested, ensure the expression is parallel safe too. + * If requested, ensure the sort expression is parallel-safe too. */ - if (!find_em_expr_usable_for_sorting_rel(root, pathkey_ec, rel, - require_parallel_safe)) + if (!relation_can_be_sorted_early(root, rel, pathkey_ec, + require_parallel_safe)) break; npathkeys++; |