Redefine create_upper_paths_hook as being invoked once per upper relation.

Per discussion, this gives potential users of the hook more flexibility,
because they can build custom Paths that implement only one stage of
upper processing atop core-provided Paths for earlier stages.

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index b2a9a8088f61d855945e5ec57eb7298a056a091d..7c1e3d6bbfd29ae9c2f8bc916262d7c7c5776381 100644 (file)
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -62,7 +62,7 @@ int           force_parallel_mode = FORCE_PARALLEL_OFF;
 /* Hook for plugins to get control in planner() */
 planner_hook_type planner_hook = NULL;
 
-/* Hook for plugins to get control before grouping_planner plans upper rels */
+/* Hook for plugins to get control when grouping_planner() plans upper rels */
 create_upper_paths_hook_type create_upper_paths_hook = NULL;
 
 
@@ -1772,20 +1772,20 @@ grouping_planner(PlannerInfo *root, bool inheritance_update,
        root->upper_targets[UPPERREL_GROUP_AGG] = grouping_target;
 
        /*
-        * Let extensions, particularly FDWs and CustomScan providers,
-        * consider injecting extension Paths into the query's upperrels,
-        * where they will compete with the Paths we create below.  We pass
-        * the final scan/join rel because that's not so easily findable from
-        * the PlannerInfo struct; anything else the hooks want to know should
-        * be obtainable via "root".
+        * If there is an FDW that's responsible for the final scan/join rel,
+        * let it consider injecting extension Paths into the query's
+        * upperrels, where they will compete with the Paths we create below.
+        * We pass the final scan/join rel because that's not so easily
+        * findable from the PlannerInfo struct; anything else the FDW wants
+        * to know should be obtainable via "root".
+        *
+        * Note: CustomScan providers, as well as FDWs that don't want to
+        * use this hook, can use the create_upper_paths_hook; see below.
         */
        if (current_rel->fdwroutine &&
            current_rel->fdwroutine->GetForeignUpperPaths)
            current_rel->fdwroutine->GetForeignUpperPaths(root, current_rel);
 
-       if (create_upper_paths_hook)
-           (*create_upper_paths_hook) (root, current_rel);
-
        /*
         * If we have grouping and/or aggregation, consider ways to implement
         * that.  We build a new upperrel representing the output of this
@@ -1962,6 +1962,11 @@ grouping_planner(PlannerInfo *root, bool inheritance_update,
        add_path(final_rel, path);
    }
 
+   /* Let extensions possibly add some more paths */
+   if (create_upper_paths_hook)
+       (*create_upper_paths_hook) (root, UPPERREL_FINAL,
+                                   current_rel, final_rel);
+
    /* Note: currently, we leave it to callers to do set_cheapest() */
 }
 
@@ -3724,6 +3729,11 @@ create_grouping_paths(PlannerInfo *root,
                 errmsg("could not implement GROUP BY"),
                 errdetail("Some of the datatypes only support hashing, while others only support sorting.")));
 
+   /* Let extensions possibly add some more paths */
+   if (create_upper_paths_hook)
+       (*create_upper_paths_hook) (root, UPPERREL_GROUP_AGG,
+                                   input_rel, grouped_rel);
+
    /* Now choose the best path(s) */
    set_cheapest(grouped_rel);
 
@@ -3780,6 +3790,11 @@ create_window_paths(PlannerInfo *root,
                                   activeWindows);
    }
 
+   /* Let extensions possibly add some more paths */
+   if (create_upper_paths_hook)
+       (*create_upper_paths_hook) (root, UPPERREL_WINDOW,
+                                   input_rel, window_rel);
+
    /* Now choose the best path(s) */
    set_cheapest(window_rel);
 
@@ -4056,6 +4071,11 @@ create_distinct_paths(PlannerInfo *root,
                 errmsg("could not implement DISTINCT"),
                 errdetail("Some of the datatypes only support hashing, while others only support sorting.")));
 
+   /* Let extensions possibly add some more paths */
+   if (create_upper_paths_hook)
+       (*create_upper_paths_hook) (root, UPPERREL_DISTINCT,
+                                   input_rel, distinct_rel);
+
    /* Now choose the best path(s) */
    set_cheapest(distinct_rel);
 
@@ -4117,6 +4137,11 @@ create_ordered_paths(PlannerInfo *root,
        }
    }
 
+   /* Let extensions possibly add some more paths */
+   if (create_upper_paths_hook)
+       (*create_upper_paths_hook) (root, UPPERREL_ORDERED,
+                                   input_rel, ordered_rel);
+
    /*
     * No need to bother with set_cheapest here; grouping_planner does not
     * need us to do it.

diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index a1ab4daf11a7d8e3361467d8837f6e0831ccbf5a..552b756b8b1b5da51445c02183a304889b439ee1 100644 (file)
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -206,7 +206,12 @@ plan_set_operations(PlannerInfo *root)
    /* Add only the final path to the SETOP upperrel. */
    add_path(setop_rel, path);
 
-   /* Select cheapest path (pretty easy at the moment) */
+   /* Let extensions possibly add some more paths */
+   if (create_upper_paths_hook)
+       (*create_upper_paths_hook) (root, UPPERREL_SETOP,
+                                   NULL, setop_rel);
+
+   /* Select cheapest path */
    set_cheapest(setop_rel);
 
    return setop_rel;

diff --git a/src/include/optimizer/planner.h b/src/include/optimizer/planner.h
index a95e73fa93b4e36f83dd0c79b8b3b2160ec87729..4161bcf8d745221a6acec7f0f721b96ef07984c1 100644 (file)
--- a/src/include/optimizer/planner.h
+++ b/src/include/optimizer/planner.h
@@ -24,9 +24,11 @@ typedef PlannedStmt *(*planner_hook_type) (Query *parse,
                                                  ParamListInfo boundParams);
 extern PGDLLIMPORT planner_hook_type planner_hook;
 
-/* Hook for plugins to get control before grouping_planner plans upper rels */
+/* Hook for plugins to get control when grouping_planner() plans upper rels */
 typedef void (*create_upper_paths_hook_type) (PlannerInfo *root,
-                                                 RelOptInfo *scan_join_rel);
+                                                    UpperRelationKind stage,
+                                                      RelOptInfo *input_rel,
+                                                    RelOptInfo *output_rel);
 extern PGDLLIMPORT create_upper_paths_hook_type create_upper_paths_hook;