Abstract logic to allow for multiple kinds of child rels.

Currently, the only type of child relation is an "other member rel",
which is the child of a baserel, but in the future joins and even
upper relations may have child rels.  To facilitate that, introduce
macros that test to test for particular RelOptKind values, and use
them in various places where they help to clarify the sense of a test.
(For example, a test may allow RELOPT_OTHER_MEMBER_REL either because
it intends to allow child rels, or because it intends to allow simple
rels.)

Also, remove find_childrel_top_parent, which will not work for a
child rel that is not a baserel.  Instead, add a new RelOptInfo
member top_parent_relids to track the same kind of information in a
more generic manner.

Ashutosh Bapat, slightly tweaked by me.  Review and testing of the
patch set from which this was taken by Rajkumar Raghuwanshi and Rafia
Sabih.

Discussion: http://postgr.es/m/CA+TgmoagTnF2yqR3PT2rv=om=wJiZ4-A+ATwdnriTGku1CLYxA@mail.gmail.com

1 files changed, 22 insertions, 29 deletions

diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c
index 7912df0baaa..3aa701fd843 100644
--- a/src/backend/optimizer/util/relnode.c
+++ b/src/backend/optimizer/util/relnode.c
@@ -88,7 +88,7 @@ setup_simple_rel_arrays(PlannerInfo *root)
  *	  Construct a new RelOptInfo for a base relation or 'other' relation.
  */
 RelOptInfo *
-build_simple_rel(PlannerInfo *root, int relid, RelOptKind reloptkind)
+build_simple_rel(PlannerInfo *root, int relid, RelOptInfo *parent)
 {
 	RelOptInfo *rel;
 	RangeTblEntry *rte;
@@ -103,7 +103,7 @@ build_simple_rel(PlannerInfo *root, int relid, RelOptKind reloptkind)
 	Assert(rte != NULL);
 
 	rel = makeNode(RelOptInfo);
-	rel->reloptkind = reloptkind;
+	rel->reloptkind = parent ? RELOPT_OTHER_MEMBER_REL : RELOPT_BASEREL;
 	rel->relids = bms_make_singleton(relid);
 	rel->rows = 0;
 	/* cheap startup cost is interesting iff not all tuples to be retrieved */
@@ -144,6 +144,22 @@ build_simple_rel(PlannerInfo *root, int relid, RelOptKind reloptkind)
 	rel->joininfo = NIL;
 	rel->has_eclass_joins = false;
 
+	/*
+	 * Pass top parent's relids down the inheritance hierarchy. If the parent
+	 * has top_parent_relids set, it's a direct or an indirect child of the top
+	 * parent indicated by top_parent_relids. By extention this child is also
+	 * an indirect child of that parent.
+	 */
+	if (parent)
+	{
+		if (parent->top_parent_relids)
+			rel->top_parent_relids = parent->top_parent_relids;
+		else
+			rel->top_parent_relids = bms_copy(parent->relids);
+	}
+	else
+		rel->top_parent_relids = NULL;
+
 	/* Check type of rtable entry */
 	switch (rte->rtekind)
 	{
@@ -209,7 +225,7 @@ build_simple_rel(PlannerInfo *root, int relid, RelOptKind reloptkind)
 				continue;
 
 			(void) build_simple_rel(root, appinfo->child_relid,
-									RELOPT_OTHER_MEMBER_REL);
+									rel);
 		}
 	}
 
@@ -504,6 +520,7 @@ build_join_rel(PlannerInfo *root,
 	joinrel->baserestrict_min_security = UINT_MAX;
 	joinrel->joininfo = NIL;
 	joinrel->has_eclass_joins = false;
+	joinrel->top_parent_relids = NULL;
 
 	/* Compute information relevant to the foreign relations. */
 	set_foreign_rel_properties(joinrel, outer_rel, inner_rel);
@@ -966,32 +983,6 @@ find_childrel_appendrelinfo(PlannerInfo *root, RelOptInfo *rel)
 
 
 /*
- * find_childrel_top_parent
- *		Fetch the topmost appendrel parent rel of an appendrel child rel.
- *
- * Since appendrels can be nested, a child could have multiple levels of
- * appendrel ancestors.  This function locates the topmost ancestor,
- * which will be a regular baserel not an otherrel.
- */
-RelOptInfo *
-find_childrel_top_parent(PlannerInfo *root, RelOptInfo *rel)
-{
-	do
-	{
-		AppendRelInfo *appinfo = find_childrel_appendrelinfo(root, rel);
-		Index		prelid = appinfo->parent_relid;
-
-		/* traverse up to the parent rel, loop if it's also a child rel */
-		rel = find_base_rel(root, prelid);
-	} while (rel->reloptkind == RELOPT_OTHER_MEMBER_REL);
-
-	Assert(rel->reloptkind == RELOPT_BASEREL);
-
-	return rel;
-}
-
-
-/*
  * find_childrel_parents
  *		Compute the set of parent relids of an appendrel child rel.
  *
@@ -1004,6 +995,8 @@ find_childrel_parents(PlannerInfo *root, RelOptInfo *rel)
 {
 	Relids		result = NULL;
 
+	Assert(rel->reloptkind == RELOPT_OTHER_MEMBER_REL);
+
 	do
 	{
 		AppendRelInfo *appinfo = find_childrel_appendrelinfo(root, rel);