diff --git a/source/libs/tdb/src/db/btree.c b/source/libs/tdb/src/db/btree.c
index 6dea4a4e57392be988126c579648f39a8270b9bf..2ce1e62c16c2292457c8b5c05774113df82ee1b1 100644
--- a/source/libs/tdb/src/db/btree.c
+++ b/source/libs/tdb/src/db/btree.c
@@ -11,4 +11,6 @@
  *
  * 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/>.
- */
\ No newline at end of file
+ */
+
+#include "tdbInt.h"
\ No newline at end of file
diff --git a/source/libs/tdb/src/db/pgcache.c b/source/libs/tdb/src/db/pgcache.c
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..2ce1e62c16c2292457c8b5c05774113df82ee1b1 100644
--- a/source/libs/tdb/src/db/pgcache.c
+++ b/source/libs/tdb/src/db/pgcache.c
@@ -0,0 +1,16 @@
+/*
+ * 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"
\ No newline at end of file
diff --git a/source/libs/tdb/src/db/pgfile.c b/source/libs/tdb/src/db/pgfile.c
index 6dea4a4e57392be988126c579648f39a8270b9bf..2ce1e62c16c2292457c8b5c05774113df82ee1b1 100644
--- a/source/libs/tdb/src/db/pgfile.c
+++ b/source/libs/tdb/src/db/pgfile.c
@@ -11,4 +11,6 @@
  *
  * 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/>.
- */
\ No newline at end of file
+ */
+
+#include "tdbInt.h"
\ 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 112fade741af99d0cea07157d2f2201dbf60f5f9..0a24331a362e846bf0a09dbe29252ace002e0407 100644
--- a/source/libs/tdb/src/db/tdb.c
+++ b/source/libs/tdb/src/db/tdb.c
@@ -13,61 +13,61 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include "tdb_db.h"
+#include "tdbInt.h"
 
-static int tdbOpenImpl(TDB *dbp);
+// static int tdbOpenImpl(TDB *dbp);
 
-int tdbOpen(TDB **dbpp, const char *fname, const char *dbname, uint32_t flags) {
-  TDB *       dbp;
-  TDB_MPFILE *mpf;
-  uint8_t     fileid[TDB_FILE_ID_LEN];
+// int tdbOpen(TDB **dbpp, const char *fname, const char *dbname, uint32_t flags) {
+//   TDB *       dbp;
+//   TDB_MPFILE *mpf;
+//   uint8_t     fileid[TDB_FILE_ID_LEN];
 
-  if ((dbp = (TDB *)calloc(1, sizeof(*dbp))) == NULL) {
-    return -1;
-  }
+//   if ((dbp = (TDB *)calloc(1, sizeof(*dbp))) == NULL) {
+//     return -1;
+//   }
 
-  if ((dbp->fname = strdup(fname)) == NULL) {
-    free(dbp);
-    return -1;
-  }
+//   if ((dbp->fname = strdup(fname)) == NULL) {
+//     free(dbp);
+//     return -1;
+//   }
 
-  if ((dbname) && ((dbp->dbname = strdup(dbname)) == NULL)) {
-    free(dbp->fname);
-    free(dbp);
-    return -1;
-  }
+//   if ((dbname) && ((dbp->dbname = strdup(dbname)) == NULL)) {
+//     free(dbp->fname);
+//     free(dbp);
+//     return -1;
+//   }
 
-  // if (tdbGnrtFileID(fname, fileid) < 0) {
-  //   // todo
-  //   return -1;
-  // }
+//   // if (tdbGnrtFileID(fname, fileid) < 0) {
+//   //   // todo
+//   //   return -1;
+//   // }
 
-  // TODO: mpf = tdbGetMPFileByID(fileid);
-  if (mpf == NULL) {
-    // todoerr: maybe we need to create one
-    return -1;
-  }
+//   // TODO: mpf = tdbGetMPFileByID(fileid);
+//   if (mpf == NULL) {
+//     // todoerr: maybe we need to create one
+//     return -1;
+//   }
 
-  if (tdbOpenImpl(dbp) < 0) {
-    // todoerr
-    return -1;
-  }
+//   if (tdbOpenImpl(dbp) < 0) {
+//     // todoerr
+//     return -1;
+//   }
 
-  *dbpp = dbp;
-  return 0;
-}
+//   *dbpp = dbp;
+//   return 0;
+// }
 
-int tdbClose(TDB *dbp, uint32_t flags) {
-  // TODO
-  return 0;
-}
+// int tdbClose(TDB *dbp, uint32_t flags) {
+//   // TODO
+//   return 0;
+// }
 
-static int tdbOpenImpl(TDB *dbp) {
-  if (dbp->dbname == NULL) {
-    // todo: open the DB as a master DB
-  } else {
-    // todo: open the DB as a sub-db
-  }
-  // TODO
-  return 0;
-}
\ No newline at end of file
+// static int tdbOpenImpl(TDB *dbp) {
+//   if (dbp->dbname == NULL) {
+//     // todo: open the DB as a master DB
+//   } else {
+//     // todo: open the DB as a sub-db
+//   }
+//   // TODO
+//   return 0;
+// }
\ 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 7b1b6cd2efc5d08b0e90d77a25bb6063f32b0af8..01658d5e0069d5ae2dd635f5e1e5d7c0dbf1dbc6 100644
--- a/source/libs/tdb/src/inc/btree.h
+++ b/source/libs/tdb/src/inc/btree.h
@@ -16,6 +16,8 @@
 #ifndef _TD_BTREE_H_
 #define _TD_BTREE_H_
 
+#include "tdbInt.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/source/libs/tdb/src/inc/pgfile.h b/source/libs/tdb/src/inc/pgfile.h
index f9a7435b3d97b7036f90fafb1386db85b1553f59..9c502fed9e09cd53ded204ff1997b08da5b8a874 100644
--- a/source/libs/tdb/src/inc/pgfile.h
+++ b/source/libs/tdb/src/inc/pgfile.h
@@ -16,12 +16,21 @@
 #ifndef _TD_PAGE_FILE_H_
 #define _TD_PAGE_FILE_H_
 
+#include "tdbInt.h"
+
+#include "pgcache.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 typedef struct SPgFile SPgFile;
 
+struct SPgFile {
+  char *    fname;     // backend file name
+  SPgCache *pPgCache;  // page cache underline
+};
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/source/libs/tdb/src/inc/tdbInt.h b/source/libs/tdb/src/inc/tdbInt.h
index c2ca7b0cfb06e761a493b83ce66b0b533b091a1c..3746c5f0772a38be8c7bfb099de33607113a934d 100644
--- a/source/libs/tdb/src/inc/tdbInt.h
+++ b/source/libs/tdb/src/inc/tdbInt.h
@@ -20,6 +20,8 @@
 #include "tlist.h"
 #include "tlockfree.h"
 
+#include "tdb.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -51,6 +53,8 @@ typedef int32_t pgsize_t;
 // tdb_log
 #define tdbError(var)
 
+#include "pgcache.h"
+
 // tdb util
 int tdbGnrtFileID(const char *fname, uint8_t *fileid);
 
diff --git a/source/libs/tdb/src/inc/tdb_db.h b/source/libs/tdb/src/inc/tdb_db.h
deleted file mode 100644
index 5f0529462b0f592b3d3adf927865c048d882b6f3..0000000000000000000000000000000000000000
--- a/source/libs/tdb/src/inc/tdb_db.h
+++ /dev/null
@@ -1,45 +0,0 @@
-/*
- * 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/>.
- */
-
-#ifndef _TD_TDB_DB_H_
-#define _TD_TDB_DB_H_
-
-#include "tdb_mpool.h"
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-typedef struct TDB TDB;
-
-struct TDB {
-  char *      fname;
-  char *      dbname;
-  TDB_MPFILE *mpf;
-  // union {
-  //   TDB_BTREE *btree;
-  //   TDB_HASH * hash;
-  //   TDB_HEAP * heap;
-  // } dbam;  // db access method
-};
-
-int tdbOpen(TDB **dbpp, const char *fname, const char *dbname, uint32_t flags);
-int tdbClose(TDB *dbp, uint32_t flags);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /*_TD_TDB_DB_H_*/
\ No newline at end of file