Support range data types.

Selectivity estimation functions are missing for some range type operators,
which is a TODO.

Jeff Davis

src/include/nodes/parsenodes.h

@@ -2334,6 +2334,17 @@ typedef struct AlterEnumStmt
 	bool		newValIsAfter;	/* place new enum value after neighbor? */
 } AlterEnumStmt;
 
+/* ----------------------
+ *		Create Type Statement, range types
+ * ----------------------
+ */
+typedef struct CreateRangeStmt
+{
+	NodeTag		type;
+	List	   *typeName;		/* qualified name (list of Value strings) */
+	List	   *params;			/* range parameters (list of DefElem) */
+} CreateRangeStmt;
+
 /* ----------------------
  *		Create View Statement
  * ----------------------