avoid_catalog_lookup.patch

diff --git a/src/backend/foreign/foreign.c b/src/backend/foreign/foreign.c
index 1fdd925..2e9f3f1 100644
--- a/src/backend/foreign/foreign.c
+++ b/src/backend/foreign/foreign.c
@@ -362,30 +362,6 @@ GetFdwRoutineByRelId(Oid relid)
 
 
 /*
- * Determine the relation is a foreign table.
- */
-bool
-IsForeignTable(Oid relid)
-{
-	HeapTuple	tuple;
-	Form_pg_class classForm;
-	char		relkind;
-
-	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
-	if (!HeapTupleIsValid(tuple))
-		ereport(ERROR,
-			   (errcode(ERRCODE_UNDEFINED_TABLE),
-				errmsg("relation with OID %u does not exist", relid)));
-	classForm = (Form_pg_class) GETSTRUCT(tuple);
-	relkind = classForm->relkind;
-	ReleaseSysCache(tuple);
-
-	return (relkind == RELKIND_FOREIGN_TABLE);
-}
-
-
-
-/*
  * deflist_to_tuplestore - Helper function to convert DefElem list to
  * tuplestore usable in SRF.
  */
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 6fc6825..b8e4c1f 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -1676,6 +1676,7 @@ _outRelOptInfo(StringInfo str, RelOptInfo *node)
 	WRITE_NODE_FIELD(subplan);
 	WRITE_NODE_FIELD(subrtable);
 	WRITE_NODE_FIELD(subrowmark);
+	WRITE_BOOL_FIELD(is_foreign_table);
 	WRITE_NODE_FIELD(baserestrictinfo);
 	WRITE_NODE_FIELD(joininfo);
 	WRITE_BOOL_FIELD(has_eclass_joins);
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index ae2e134..780e64c 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -256,7 +256,7 @@ set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
 	 * least one dimension of cost or sortedness.
 	 */
 
-	if (IsForeignTable(rte->relid))
+	if (rel->is_foreign_table)
 	{
 		/* only foreign scan path is applyable to foreign table */
 		add_path(rel, create_foreignscan_path(root, rel));
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 1d60af8..f86bc5f 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -339,6 +339,13 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
 
 	rel->indexlist = indexinfos;
 
+	/*
+	 * We should remember whether the relation is a foreign table or not to
+	 * avoid catalog lookup in the phase of path generation.
+	 */
+	if (relation->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
+		rel->is_foreign_table = true;
+
 	heap_close(relation, NoLock);
 
 	/*
diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c
index b7a5845..7c2a39d 100644
--- a/src/backend/optimizer/util/relnode.c
+++ b/src/backend/optimizer/util/relnode.c
@@ -85,6 +85,7 @@ build_simple_rel(PlannerInfo *root, int relid, RelOptKind reloptkind)
 	rel->subplan = NULL;
 	rel->subrtable = NIL;
 	rel->subrowmark = NIL;
+	rel->is_foreign_table = false;
 	rel->baserestrictinfo = NIL;
 	rel->baserestrictcost.startup = 0;
 	rel->baserestrictcost.per_tuple = 0;
@@ -339,6 +340,7 @@ build_join_rel(PlannerInfo *root,
 	joinrel->subplan = NULL;
 	joinrel->subrtable = NIL;
 	joinrel->subrowmark = NIL;
+	joinrel->is_foreign_table = false;
 	joinrel->baserestrictinfo = NIL;
 	joinrel->baserestrictcost.startup = 0;
 	joinrel->baserestrictcost.per_tuple = 0;
diff --git a/src/include/foreign/foreign.h b/src/include/foreign/foreign.h
index fe299b3..b0cb37c 100644
--- a/src/include/foreign/foreign.h
+++ b/src/include/foreign/foreign.h
@@ -79,6 +79,5 @@ extern Oid	GetForeignDataWrapperOidByName(const char *name, bool missing_ok);
 extern ForeignTable *GetForeignTable(Oid relid);
 extern FdwRoutine *GetFdwRoutineByRelId(Oid relid);
 extern FdwRoutine *GetFdwRoutine(Oid fdwhandler);
-extern bool IsForeignTable(Oid relid);
 
 #endif   /* FOREIGN_H */
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index 133a2bd..5abbb07 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -395,6 +395,7 @@ typedef struct RelOptInfo
 	struct Plan *subplan;		/* if subquery */
 	List	   *subrtable;		/* if subquery */
 	List	   *subrowmark;		/* if subquery */
+	bool		is_foreign_table;	/* T means relation is a foreign table */
 
 	/* used by various scans and joins: */
 	List	   *baserestrictinfo;		/* RestrictInfo structures (if base