From 3d2c58b65aeecbd6484a31066ccc8b8f2ede583b Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Fri, 23 Feb 2018 11:53:07 -0500 Subject: [PATCH 1/4] Let Parallel Append over simple UNION ALL have partial subpaths. A simple UNION ALL gets flattened into an appendrel of subquery RTEs, but up until now it's been impossible for the appendrel to use the partial paths for the subqueries, so we can implement the appendrel as a Parallel Append but only one with non-partial paths as children. There are three separate obstacles to removing that limitation. First, when planning a subquery, propagate any partial paths to the final_rel so that they are potentially visible to outer query levels. Second, after planning a subquery, propagate any partial paths for the final_rel to the subquery RTE in the outer query level in the same way we do for non-partial paths. Third, teach finalize_plan() to account for the possibility that the fake parameter we use for rescan signalling when the plan contains a Gather (Merge) node may be propagated from an outer query level. Patch by me. Discussion: http://postgr.es/m/CA+Tgmoa6L9A1nNCk3aTDVZLZ4KkHDn1+tm7mFyFvP+uQPS7bAg@mail.gmail.com --- src/backend/optimizer/path/allpaths.c | 22 ++++++++++++++++++++++ src/backend/optimizer/plan/planner.c | 16 ++++++++++++++++ src/backend/optimizer/plan/subselect.c | 10 ++++++++-- 3 files changed, 46 insertions(+), 2 deletions(-) diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index f714247ebb..f15bddc575 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -2179,6 +2179,28 @@ set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel, create_subqueryscan_path(root, rel, subpath, pathkeys, required_outer)); } + + /* If consider_parallel is false, there should be no partial paths. */ + Assert(sub_final_rel->consider_parallel || + sub_final_rel->partial_pathlist == NIL); + + /* Same for partial paths. */ + foreach(lc, sub_final_rel->partial_pathlist) + { + Path *subpath = (Path *) lfirst(lc); + List *pathkeys; + + /* Convert subpath's pathkeys to outer representation */ + pathkeys = convert_subquery_pathkeys(root, + rel, + subpath->pathkeys, + make_tlist_from_pathtarget(subpath->pathtarget)); + + /* Generate outer path using this subpath */ + add_partial_path(rel, (Path *) + create_subqueryscan_path(root, rel, subpath, + pathkeys, required_outer)); + } } /* diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c index 3e8cd1447c..6a4c5d35a6 100644 --- a/src/backend/optimizer/plan/planner.c +++ b/src/backend/optimizer/plan/planner.c @@ -2161,6 +2161,22 @@ grouping_planner(PlannerInfo *root, bool inheritance_update, add_path(final_rel, path); } + /* + * Generate partial paths for final_rel, too, if outer query levels might + * be able to make use of them. + */ + if (final_rel->consider_parallel && root->query_level > 1 && + !limit_needed(parse)) + { + Assert(!parse->rowMarks && parse->commandType == CMD_SELECT); + foreach(lc, current_rel->partial_pathlist) + { + Path *partial_path = (Path *) lfirst(lc); + + add_partial_path(final_rel, partial_path); + } + } + /* * If there is an FDW that's responsible for all baserels of the query, * let it consider adding ForeignPaths. diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c index 46367cba63..680ffd2cf9 100644 --- a/src/backend/optimizer/plan/subselect.c +++ b/src/backend/optimizer/plan/subselect.c @@ -2407,10 +2407,16 @@ finalize_plan(PlannerInfo *root, Plan *plan, { SubqueryScan *sscan = (SubqueryScan *) plan; RelOptInfo *rel; + Bitmapset *subquery_params; - /* We must run SS_finalize_plan on the subquery */ + /* We must run finalize_plan on the subquery */ rel = find_base_rel(root, sscan->scan.scanrelid); - SS_finalize_plan(rel->subroot, sscan->subplan); + subquery_params = rel->subroot->outer_params; + if (gather_param >= 0) + subquery_params = bms_add_member(bms_copy(subquery_params), + gather_param); + finalize_plan(rel->subroot, sscan->subplan, gather_param, + subquery_params, NULL); /* Now we can add its extParams to the parent's params */ context.paramids = bms_add_members(context.paramids, -- 2.14.3 (Apple Git-98)