diff --git a/source/libs/tdb/inc/tdb.h b/source/libs/tdb/inc/tdb.h
index de83824170..e02f0f32b7 100644
--- a/source/libs/tdb/inc/tdb.h
+++ b/source/libs/tdb/inc/tdb.h
@@ -23,10 +23,11 @@ extern "C" {
 #endif
 
 typedef struct STDb TDB;
+typedef struct STDbEnv TENV;
 
 int tdbCreate(TDB **ppDb);
 int tdbDestroy(TDB *pDb);
-int tdbOpen(TDB **pDb);
+int tdbOpen(TDB **pDb, const char *fname, const char *dbname);
 int tdbClose(TDB *pDb);
 
 #ifdef __cplusplus
diff --git a/source/libs/tdb/src/db/btree.c b/source/libs/tdb/src/db/btree.c
index 845bddc8b5..746ca6a99a 100644
--- a/source/libs/tdb/src/db/btree.c
+++ b/source/libs/tdb/src/db/btree.c
@@ -15,11 +15,6 @@
 
 #include "tdbInt.h"
 
-struct SBTree {
-  pgno_t root;
-  // TODO
-};
-
 struct SBtCursor {
   // TODO
 };
\ No newline at end of file
diff --git a/source/libs/tdb/src/db/tdb.c b/source/libs/tdb/src/db/tdb.c
index ea819b34e7..f922a04ceb 100644
--- a/source/libs/tdb/src/db/tdb.c
+++ b/source/libs/tdb/src/db/tdb.c
@@ -16,8 +16,8 @@
 #include "tdbInt.h"
 
 struct STDb {
-  // TODO
-  SBTree *pBt;
+  SBTree   btree;    // current access method
+  SPgFile *pPgFile;  // backend page file this DB is using
 };
 
 int tdbCreate(TDB **ppDb) {
@@ -41,7 +41,7 @@ int tdbDestroy(TDB *pDb) {
   return 0;
 }
 
-int tdbOpen(TDB **pDb) {
+int tdbOpen(TDB **pDb, const char *fname, const char *dbname) {
   // TODO
   return 0;
 }
diff --git a/source/libs/tdb/src/db/tdbEnv.c b/source/libs/tdb/src/db/tdbEnv.c
new file mode 100644
index 0000000000..aae92f2bed
--- /dev/null
+++ b/source/libs/tdb/src/db/tdbEnv.c
@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "tdbInt.h"
+
+struct STDbEnv {
+  TDB *    dbList;      // TDB list
+  SPgFile *pgFileList;  // SPgFile list
+};
\ No newline at end of file
diff --git a/source/libs/tdb/src/inc/btree.h b/source/libs/tdb/src/inc/btree.h
index 4b6fe589a9..2aa2f4528f 100644
--- a/source/libs/tdb/src/inc/btree.h
+++ b/source/libs/tdb/src/inc/btree.h
@@ -32,6 +32,10 @@ int btreeCursorOpen(SBtCursor *pBtCur, SBTree *pBt);
 int btreeCursorClose(SBtCursor *pBtCur);
 int btreeCursorMoveTo(SBtCursor *pBtCur);
 
+struct SBTree {
+  pgno_t root;
+};
+
 #ifdef __cplusplus
 }
 #endif