Support namespacing within RMS db

store/rootmultistore.go

@@ -56,8 +56,9 @@ func (rs *rootMultiStore) MountStoreWithDB(key StoreKey, typ StoreType, db dbm.D
 		panic(fmt.Sprintf("rootMultiStore duplicate store key %v", key))
 	}
 	rs.storesParams[key] = storeParams{
-		db:  db,
+		key: key,
 		typ: typ,
+		db:  db,
 	}
 	rs.keysByName[key.Name()] = key
 }
@@ -244,9 +245,12 @@ func parsePath(path string) (storeName string, subpath string, err sdk.Error) {
 //----------------------------------------
 
 func (rs *rootMultiStore) loadCommitStoreFromParams(id CommitID, params storeParams) (store CommitStore, err error) {
-	db := rs.db
+	var db dbm.DB
 	if params.db != nil {
 		db = params.db
+	} else {
+		db = rs.db
+		db = dbm.NewPrefixDB(rs.db, []byte(params.key.Name()))
 	}
 	switch params.typ {
 	case sdk.StoreTypeMulti:
@@ -276,6 +280,7 @@ func (rs *rootMultiStore) nameToKey(name string) StoreKey {
 // storeParams
 
 type storeParams struct {
+	key StoreKey
 	db  dbm.DB
 	typ StoreType
 }