Fix search for mchar/mvarchar tuypes via search_path to make these types dumpable even with cleaned up searchpath

Author: vbwagner

src/backend/optimizer/path/indxpath.c

@@ -3258,6 +3258,38 @@ static Oid mmGTOid = InvalidOid;
 static Oid mcharOid = InvalidOid; 
 static Oid mvarcharOid = InvalidOid;
 
+static Oid
+findTypeOid(char *typname)
+{
+	CatCList	*catlist;
+	HeapTuple	tup;
+	int			n_members;
+	Oid			typoid;
+
+	catlist = SearchSysCacheList(TYPENAMENSP, 1,
+								 CStringGetDatum(typname),
+								 0, 0, 0);
+
+	n_members = catlist->n_members;
+
+	if (n_members != 1)
+	{
+		ReleaseSysCacheList(catlist);
+		if (n_members > 1)
+			elog(ERROR,"There are %d candidates for '%s' type",
+				 n_members, typname);
+		return InvalidOid;
+	}
+
+	tup = &catlist->members[0]->tuple;
+
+	typoid = HeapTupleGetOid(tup);
+
+	ReleaseSysCacheList(catlist);
+
+	return typoid;
+}
+
 static bool
 fillMCharOIDS() {
 	CatCList    *catlist;
@@ -3280,27 +3312,13 @@ fillMCharOIDS() {
 	tup = &catlist->members[0]->tuple;
 
 	if ( HeapTupleGetOid(tup) != mmPFPOid ) {
-		TypeName	*typename;
-		Type		typtup;
 		char        *quals_funcname = "mchar_greaterstring";
 		Oid			tmp_mmPFPOid = HeapTupleGetOid(tup);
 
 		ReleaseSysCacheList(catlist);
 
-		typename = makeTypeName("mchar");
-		typtup = LookupTypeName(NULL, typename, NULL, true);
-		if ( typtup ) {
-			mcharOid = typeTypeId(typtup);
-			ReleaseSysCache(typtup);
-		}
-
-		typename = makeTypeName("mvarchar");
-		typtup = LookupTypeName(NULL, typename, NULL, true);
-		if ( typtup ) {
-			mvarcharOid = typeTypeId(typtup);
-			ReleaseSysCache(typtup);
-		}
-
+		mcharOid = findTypeOid("mchar");
+		mvarcharOid = findTypeOid("mvarchar");
 
 		if ( mcharOid == InvalidOid || mvarcharOid == InvalidOid ) {
 			elog(LOG,"Can't find mchar/mvarvarchar types: mchar=%d mvarchar=%d",