Add a relkind field to RangeTblEntry to avoid some syscache lookups.

The recent additions for FDW support required checking foreign-table-ness
in several places in the parse/plan chain.  While it's not clear whether
that would really result in a noticeable slowdown, it seems best to avoid
any performance risk by keeping a copy of the relation's relkind in
RangeTblEntry.  That might have some other uses later, anyway.
Per discussion.

2 files changed, 37 insertions, 33 deletions

diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index c835a954ed9..dc2a23bb273 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -176,41 +176,44 @@ set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
 		/* It's an "append relation", process accordingly */
 		set_append_rel_pathlist(root, rel, rti, rte);
 	}
-	else if (rel->rtekind == RTE_SUBQUERY)
-	{
-		/* Subquery --- generate a separate plan for it */
-		set_subquery_pathlist(root, rel, rti, rte);
-	}
-	else if (rel->rtekind == RTE_FUNCTION)
-	{
-		/* RangeFunction --- generate a suitable path for it */
-		set_function_pathlist(root, rel, rte);
-	}
-	else if (rel->rtekind == RTE_VALUES)
-	{
-		/* Values list --- generate a suitable path for it */
-		set_values_pathlist(root, rel, rte);
-	}
-	else if (rel->rtekind == RTE_CTE)
-	{
-		/* CTE reference --- generate a suitable path for it */
-		if (rte->self_reference)
-			set_worktable_pathlist(root, rel, rte);
-		else
-			set_cte_pathlist(root, rel, rte);
-	}
 	else
 	{
-		Assert(rel->rtekind == RTE_RELATION);
-		if (get_rel_relkind(rte->relid) == RELKIND_FOREIGN_TABLE)
-		{
-			/* Foreign table */
-			set_foreign_pathlist(root, rel, rte);
-		}
-		else
+		switch (rel->rtekind)
 		{
-			/* Plain relation */
-			set_plain_rel_pathlist(root, rel, rte);
+			case RTE_RELATION:
+				if (rte->relkind == RELKIND_FOREIGN_TABLE)
+				{
+					/* Foreign table */
+					set_foreign_pathlist(root, rel, rte);
+				}
+				else
+				{
+					/* Plain relation */
+					set_plain_rel_pathlist(root, rel, rte);
+				}
+				break;
+			case RTE_SUBQUERY:
+				/* Subquery --- generate a separate plan for it */
+				set_subquery_pathlist(root, rel, rti, rte);
+				break;
+			case RTE_FUNCTION:
+				/* RangeFunction --- generate a suitable path for it */
+				set_function_pathlist(root, rel, rte);
+				break;
+			case RTE_VALUES:
+				/* Values list --- generate a suitable path for it */
+				set_values_pathlist(root, rel, rte);
+				break;
+			case RTE_CTE:
+				/* CTE reference --- generate a suitable path for it */
+				if (rte->self_reference)
+					set_worktable_pathlist(root, rel, rte);
+				else
+					set_cte_pathlist(root, rel, rte);
+				break;
+			default:
+				elog(ERROR, "unexpected rtekind: %d", (int) rel->rtekind);
+				break;
 		}
 	}
 
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index b73b872b312..ee09673051f 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -1915,7 +1915,7 @@ preprocess_rowmarks(PlannerInfo *root)
 		newrc->rowmarkId = ++(root->glob->lastRowMarkId);
 		/* real tables support REFERENCE, anything else needs COPY */
 		if (rte->rtekind == RTE_RELATION &&
-			get_rel_relkind(rte->relid) != RELKIND_FOREIGN_TABLE)
+			rte->relkind != RELKIND_FOREIGN_TABLE)
 			newrc->markType = ROW_MARK_REFERENCE;
 		else
 			newrc->markType = ROW_MARK_COPY;
@@ -3078,6 +3078,7 @@ plan_cluster_use_sort(Oid tableOid, Oid indexOid)
 	rte = makeNode(RangeTblEntry);
 	rte->rtekind = RTE_RELATION;
 	rte->relid = tableOid;
+	rte->relkind = RELKIND_RELATION;
 	rte->inh = false;
 	rte->inFromCl = true;
 	query->rtable = list_make1(rte);