diff options
Diffstat (limited to 'src/backend/optimizer/path/allpaths.c')
| -rw-r--r-- | src/backend/optimizer/path/allpaths.c | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index 358bb2aed6f..028d9e16808 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -2451,6 +2451,7 @@ set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel, { Query *parse = root->parse; Query *subquery = rte->subquery; + bool trivial_pathtarget; Relids required_outer; pushdown_safety_info safetyInfo; double tuple_fraction; @@ -2614,6 +2615,36 @@ set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel, set_subquery_size_estimates(root, rel); /* + * Also detect whether the reltarget is trivial, so that we can pass that + * info to cost_subqueryscan (rather than re-deriving it multiple times). + * It's trivial if it fetches all the subplan output columns in order. + */ + if (list_length(rel->reltarget->exprs) != list_length(subquery->targetList)) + trivial_pathtarget = false; + else + { + trivial_pathtarget = true; + foreach(lc, rel->reltarget->exprs) + { + Node *node = (Node *) lfirst(lc); + Var *var; + + if (!IsA(node, Var)) + { + trivial_pathtarget = false; + break; + } + var = (Var *) node; + if (var->varno != rti || + var->varattno != foreach_current_index(lc) + 1) + { + trivial_pathtarget = false; + break; + } + } + } + + /* * For each Path that subquery_planner produced, make a SubqueryScanPath * in the outer query. */ @@ -2631,6 +2662,7 @@ set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel, /* Generate outer path using this subpath */ add_path(rel, (Path *) create_subqueryscan_path(root, rel, subpath, + trivial_pathtarget, pathkeys, required_outer)); } @@ -2656,6 +2688,7 @@ set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel, /* Generate outer path using this subpath */ add_partial_path(rel, (Path *) create_subqueryscan_path(root, rel, subpath, + trivial_pathtarget, pathkeys, required_outer)); } |