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

3 files changed, 20 insertions, 9 deletions

diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index 343b35aa326..b93b4fc7736 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -539,8 +539,7 @@ set_rel_consider_parallel(PlannerInfo *root, RelOptInfo *rel,
 	Assert(root->glob->parallelModeOK);
 
 	/* This should only be called for baserels and appendrel children. */
-	Assert(rel->reloptkind == RELOPT_BASEREL ||
-		   rel->reloptkind == RELOPT_OTHER_MEMBER_REL);
+	Assert(IS_SIMPLE_REL(rel));
 
 	/* Assorted checks based on rtekind. */
 	switch (rte->rtekind)
@@ -846,7 +845,7 @@ set_foreign_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
 
 /*
  * set_append_rel_size
- *	  Set size estimates for an "append relation"
+ *	  Set size estimates for a simple "append relation"
  *
  * The passed-in rel and RTE represent the entire append relation.  The
  * relation's contents are computed by appending together the output of
@@ -867,6 +866,8 @@ set_append_rel_size(PlannerInfo *root, RelOptInfo *rel,
 	int			nattrs;
 	ListCell   *l;
 
+	Assert(IS_SIMPLE_REL(rel));
+
 	/*
 	 * Initialize to compute size estimates for whole append relation.
 	 *
diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c
index a329dd1e10d..67bd760fb47 100644
--- a/src/backend/optimizer/path/equivclass.c
+++ b/src/backend/optimizer/path/equivclass.c
@@ -1060,10 +1060,12 @@ generate_join_implied_equalities_for_ecs(PlannerInfo *root,
 	ListCell   *lc;
 
 	/* If inner rel is a child, extra setup work is needed */
-	if (inner_rel->reloptkind == RELOPT_OTHER_MEMBER_REL)
+	if (IS_OTHER_REL(inner_rel))
 	{
+		Assert(!bms_is_empty(inner_rel->top_parent_relids));
+
 		/* Fetch relid set for the topmost parent rel */
-		nominal_inner_relids = find_childrel_top_parent(root, inner_rel)->relids;
+		nominal_inner_relids = inner_rel->top_parent_relids;
 		/* ECs will be marked with the parent's relid, not the child's */
 		nominal_join_relids = bms_union(outer_relids, nominal_inner_relids);
 	}
@@ -1324,8 +1326,7 @@ generate_join_implied_equalities_broken(PlannerInfo *root,
 	 * mentioned in the ec_sources clauses, we have to be prepared to apply
 	 * multiple levels of Var translation.
 	 */
-	if (inner_rel->reloptkind == RELOPT_OTHER_MEMBER_REL &&
-		result != NIL)
+	if (IS_OTHER_REL(inner_rel) && result != NIL)
 		result = (List *) adjust_appendrel_attrs_multilevel(root,
 															(Node *) result,
 															inner_rel);
@@ -2180,6 +2181,9 @@ generate_implied_equalities_for_column(PlannerInfo *root,
 	Relids		parent_relids;
 	ListCell   *lc1;
 
+	/* Indexes are available only on base or "other" member relations. */
+	Assert(IS_SIMPLE_REL(rel));
+
 	/* If it's a child rel, we'll need to know what its parent(s) are */
 	if (is_child_rel)
 		parent_relids = find_childrel_parents(root, rel);
@@ -2413,8 +2417,11 @@ eclass_useful_for_merging(PlannerInfo *root,
 	 */
 
 	/* If specified rel is a child, we must consider the topmost parent rel */
-	if (rel->reloptkind == RELOPT_OTHER_MEMBER_REL)
-		relids = find_childrel_top_parent(root, rel)->relids;
+	if (IS_OTHER_REL(rel))
+	{
+		Assert(!bms_is_empty(rel->top_parent_relids));
+		relids = rel->top_parent_relids;
+	}
 	else
 		relids = rel->relids;
 
diff --git a/src/backend/optimizer/path/indxpath.c b/src/backend/optimizer/path/indxpath.c
index a5d19f9b1c5..cec9822cb79 100644
--- a/src/backend/optimizer/path/indxpath.c
+++ b/src/backend/optimizer/path/indxpath.c
@@ -2779,6 +2779,9 @@ check_index_predicates(PlannerInfo *root, RelOptInfo *rel)
 	Relids		otherrels;
 	ListCell   *lc;
 
+	/* Indexes are available only on base or "other" member relations. */
+	Assert(IS_SIMPLE_REL(rel));
+
 	/*
 	 * Initialize the indrestrictinfo lists to be identical to
 	 * baserestrictinfo, and check whether there are any partial indexes.  If