diff --git a/src/vnode/common/catalog/inc/type.h b/src/vnode/common/catalog/inc/type.h
index ed8d84a22785e4e51f2262a426c08c1240edccb2..69aee2a5de6dc73f476cb465977d2e90f6341102 100644
--- a/src/vnode/common/catalog/inc/type.h
+++ b/src/vnode/common/catalog/inc/type.h
@@ -1,7 +1,9 @@
 #if !defined(_TD_TYPE_H_)
 #define _TD_TYPE_H_
 
-typedef enum {
+#include <stdint.h>
+
+typedef enum : uint8_t {
     TD_DATATYPE_INVLD = 0,
     TD_DATATYPE_BOOL,
     TD_DATATYPE_TINYINT,
diff --git a/src/vnode/common/tstr/inc/tstring.h b/src/vnode/common/tstr/inc/tstring.h
index f7cea231f8d48a5d510f8f3b9487a984c1fb8138..742069b9db7aed819e45c5a0f128b7285abbb288 100644
--- a/src/vnode/common/tstr/inc/tstring.h
+++ b/src/vnode/common/tstr/inc/tstring.h
@@ -4,21 +4,37 @@
 #define _TD_TSTRING_H_
 
 #include <stdint.h>
+#include <string.h>
+
+#define TD_TSTRING_INIT_SIZE 16
 
 typedef char* tstring_t;
 
 // The string header
 typedef struct {
-    int32_t strLen;  // Allocated data space
-    int32_t avail;   // Available space
+    int32_t space;  // Allocated data space
     char data[];
 } STStrHdr;
 
 // Get the data length of the string
-#define TSTRLEN(pstr) ((STStrHdr *)pstr)->strLen
-// Get the available space
-#define TSTRAVAIL(pstr) ((STStrHdr *)pstr)->avail
+#define TSTRLEN(pstr) strlen((char *)pstr)
 // Get the real allocated string length
-#define TSTRRLEN(pstr) ((STStrHdr *)pstr)->strLen + sizeof(STStrHdr)
+#define TSTRSPACE(pstr) (*(int32_t *)((char *)pstr - sizeof(STStrHdr)))
+// Get the available space
+#define TSTAVAIL(pstr) (TSTRSPACE(pstr) - TSTRLEN(pstr))
+
+// Create an empty tstring with default size
+tstring_t tdNewTString();
+// Create an empty tstring with size
+tstring_t tdNewTStringWithSize(uint32_t size);
+// Create a tstring with a init value
+tstring_t tdNewTStringWithValue(char *value);
+// Create a tstring with a init value & size
+tstring_t tdNewTStringWithValueSize(char *value, uint32_t size);
+
+tstring_t tstrcat(tstring_t dest, tstring_t src);
+int32_t   tstrcmp(tstring_t str1, tstring_t str2);
+int32_t   tstrncmp(tstring_t str1, tstring_t str2, int32_t n);
+
 
 #endif // _TD_TSTRING_H_
diff --git a/src/vnode/tsdb/inc/tsdbFile.h b/src/vnode/tsdb/inc/tsdbFile.h
new file mode 100644
index 0000000000000000000000000000000000000000..a4cfa595550252e506195875b0e41a245e465541
--- /dev/null
+++ b/src/vnode/tsdb/inc/tsdbFile.h
@@ -0,0 +1,29 @@
+#if !defined(_TD_TSDB_FILE_H_)
+#define _TD_TSDB_FILE_H_
+
+#include "tstring.h"
+
+typedef int32_t file_id_t;
+
+typedef enum : uint8_t {
+  TSDB_FILE_TYPE_HEAD,
+  TSDB_FILE_TYPE_DATA,
+  TSDB_FILE_TYPE_LAST,
+  TSDB_FILE_TYPE_META
+} TSDB_FILE_TYPE;
+
+typedef struct {
+  int64_t fileSize;
+} SFileInfo;
+
+typedef struct {
+  tstring_t fname;
+  SFileInfo;
+} SFILE;
+
+tstring_t tdGetHeadFileName(/* TODO */);
+tstring_t tdGetDataFileName(/* TODO */);
+tstring_t tdGetLastFileName(/* TODO */);
+tstring_t tdGetMetaFileName(/* TODO */);
+
+#endif  // _TD_TSDB_FILE_H_
diff --git a/src/vnode/tsdb/inc/tsdbMeta.h b/src/vnode/tsdb/inc/tsdbMeta.h
index 9ab39171a6ebce27bed7a60d1d6f9f4a76797149..684e80160f13bbadffb527cfb3eb8490aa1da136 100644
--- a/src/vnode/tsdb/inc/tsdbMeta.h
+++ b/src/vnode/tsdb/inc/tsdbMeta.h
@@ -51,6 +51,9 @@ typedef struct STable {
 
   // Tag values for this table
   char *pTagVal;
+
+  // Cached data
+  SSkipList *pData;
 } STable;
 
 #define TSDB_GET_TABLE_ID(pTable) (((STable *)pTable)->tid).tableId