diff options
Diffstat (limited to 'src/backend/optimizer/prep/prepunion.c')
| -rw-r--r-- | src/backend/optimizer/prep/prepunion.c | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c index 30068c27a13..1c69c6e97e8 100644 --- a/src/backend/optimizer/prep/prepunion.c +++ b/src/backend/optimizer/prep/prepunion.c @@ -498,7 +498,7 @@ generate_recursion_path(SetOperationStmt *setOp, PlannerInfo *root, * interesting_pathkeys: if not NIL, also include paths that suit these * pathkeys, sorting any unsorted paths as required. * *pNumGroups: if not NULL, we estimate the number of distinct groups - * in the result, and store it there + * in the result, and store it there. */ static void build_setop_child_paths(PlannerInfo *root, RelOptInfo *rel, @@ -714,7 +714,7 @@ generate_union_paths(SetOperationStmt *op, PlannerInfo *root, List *groupList = NIL; Path *apath; Path *gpath = NULL; - bool try_sorted; + bool try_sorted = false; List *union_pathkeys = NIL; /* @@ -740,18 +740,21 @@ generate_union_paths(SetOperationStmt *op, PlannerInfo *root, tlist_list, refnames_tlist); *pTargetList = tlist; - /* For for UNIONs (not UNION ALL), try sorting, if sorting is possible */ - try_sorted = !op->all && grouping_is_sortable(op->groupClauses); - - if (try_sorted) + /* For UNIONs (not UNION ALL), try sorting, if sorting is possible */ + if (!op->all) { /* Identify the grouping semantics */ groupList = generate_setop_grouplist(op, tlist); - /* Determine the pathkeys for sorting by the whole target list */ - union_pathkeys = make_pathkeys_for_sortclauses(root, groupList, tlist); + if (grouping_is_sortable(op->groupClauses)) + { + try_sorted = true; + /* Determine the pathkeys for sorting by the whole target list */ + union_pathkeys = make_pathkeys_for_sortclauses(root, groupList, + tlist); - root->query_pathkeys = union_pathkeys; + root->query_pathkeys = union_pathkeys; + } } /* |