diff --git a/src/vnode/cache/inc/cache.h b/src/vnode/cache/inc/cache.h
index c90c47a62183eb58ac77c502e430640dc16c8cb8..52f357ee8f133d5110c91df99d0f52328eed2093 100644
--- a/src/vnode/cache/inc/cache.h
+++ b/src/vnode/cache/inc/cache.h
@@ -1,12 +1,14 @@
 #if !defined(_TD_CACHE_H_)
 #define _TD_CACHE_H_
 
+#define TD_MIN_CACHE_BLOCK_SIZE 1024*1024    /* 1M */
+#define TD_MAX_CACHE_BLOCK_SIZE 64*1024*1024 /* 64M */
+
 typedef void cache_pool_t;
 
 typedef struct SCacheBlock
 {
-    SCacheBlock *next;
-    SCacheBlock *prev;
+    int32_t blockId;
     char data[];
 } SCacheBlock;
 
diff --git a/src/vnode/common/catalog/inc/schema.h b/src/vnode/common/catalog/inc/schema.h
index 89a048574c959cabc0b5caf35e5a0d50beee6a6e..add0fdd9a1c94bf64fcf698f28b9974deb897ce2 100644
--- a/src/vnode/common/catalog/inc/schema.h
+++ b/src/vnode/common/catalog/inc/schema.h
@@ -3,6 +3,7 @@
 
 #include <stdint.h>
 
+#include "tstring.h"
 #include "type.h"
 
 typedef struct _scolumn {
@@ -15,4 +16,25 @@ typedef struct SSchema {
   SColumn *columns;
 } SSchema;
 
+// Column with version
+typedef struct {
+  td_datatype_t type;
+  int32_t colId;
+  int32_t bytes;
+} SVColumn;
+
+// Schema with version
+typedef struct {
+  int32_t version;      // Schema with version
+  int32_t numOfCols;
+  int32_t columnId;
+  SVColumn *columns;
+} SVSchema;
+
+int32_t tdAddColumnToSchema(tstring_t pSchema, SColumn col);
+
+td_datatype_t tdGetTypeOfCol(SSchema *pSchema, int32_t col);
+int32_t tdGetLengthOfCol(SSchema *pSchema, int32_t col);
+
+
 #endif  // _TD_SCHEMA_H_
diff --git a/src/vnode/common/data/inc/data.h b/src/vnode/common/data/inc/data.h
index 5ccecd4718b8ba6346ff8b7472b4732052146b20..376837502560e8671735aa7d343cef98d9921d20 100644
--- a/src/vnode/common/data/inc/data.h
+++ b/src/vnode/common/data/inc/data.h
@@ -3,6 +3,8 @@
 
 #include <stdint.h>
 
+#include "schema.h"
+
 /* The row data should in the form of
  */
 
diff --git a/src/vnode/common/datastructure/inc/dlist.h b/src/vnode/common/datastructure/inc/dlist.h
new file mode 100644
index 0000000000000000000000000000000000000000..81a3b32ab022ee7e9c937e3981316c2fcb1ed205
--- /dev/null
+++ b/src/vnode/common/datastructure/inc/dlist.h
@@ -0,0 +1,29 @@
+// A doubly linked list
+#if !defined(_TD_DLIST_H_)
+#define _TD_DLIST_H_
+
+#include <stdint.h>
+
+typedef struct {
+  SListNode *prev;
+  SListNode *next;
+  void *     data;
+} SListNode;
+
+// Doubly linked list
+typedef struct {
+    SListNode *head;
+    SListNode *tail;
+    int32_t length;
+} SDList;
+
+// ----- Set operation
+#define TD_GET_DLIST_LENGTH(pDList) (((SDList *)pDList)->length)
+#define TD_GET_DLIST_HEAD(pDList) (((SDList *)pDList)->head)
+#define TD_GET_DLIST_TAIL(pDList) (((SDList *)pDList)->tail)
+
+#define TD_GET_DLIST_NEXT_NODE(pDNode) (((SListNode *)pDNode)->next)
+#define TD_GET_DLIST_PREV_NODE(pDNode) (((SListNode *)pDNode)->prev)
+#define TD_GET_DLIST_NODE_DATA(pDNode) (((SListNode *)pDNode)->data)
+
+#endif  // _TD_DLIST_H_
diff --git a/src/vnode/common/tstr/inc/tstring.h b/src/vnode/common/tstr/inc/tstring.h
new file mode 100644
index 0000000000000000000000000000000000000000..f7cea231f8d48a5d510f8f3b9487a984c1fb8138
--- /dev/null
+++ b/src/vnode/common/tstr/inc/tstring.h
@@ -0,0 +1,24 @@
+/* A dynamic string library
+ */ 
+#if !defined(_TD_TSTRING_H_)
+#define _TD_TSTRING_H_
+
+#include <stdint.h>
+
+typedef char* tstring_t;
+
+// The string header
+typedef struct {
+    int32_t strLen;  // Allocated data space
+    int32_t avail;   // Available 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
+// Get the real allocated string length
+#define TSTRRLEN(pstr) ((STStrHdr *)pstr)->strLen + sizeof(STStrHdr)
+
+#endif // _TD_TSTRING_H_
diff --git a/src/vnode/tsdb/inc/tsdbCache.h b/src/vnode/tsdb/inc/tsdbCache.h
index cafb545606f8a7bc1ef15cea1e28d25a05213af1..d1d255168397dc4e22775325bc19d89e172d5d91 100644
--- a/src/vnode/tsdb/inc/tsdbCache.h
+++ b/src/vnode/tsdb/inc/tsdbCache.h
@@ -4,11 +4,19 @@
 #include <stdint.h>
 
 #include "cache.h"
+#include "dlist.h"
 
+typedef struct {
+  int64_t      blockId;
+  SCacheBlock *pBlock
+} STSDBCacheBlock;
+
+// Use a doublely linked list to implement this
 typedef struct STSDBCache {
-    int64_t blockId;  // A block ID counter
-    SCacheBlock *blockList;
+  int64_t blockId;  // A block ID counter
+  SDList *cacheList;
 } STSDBCache;
 
+STSDBCache *tsdbCreateCache();
 
-#endif // _TD_TSDBCACHE_H_
+#endif  // _TD_TSDBCACHE_H_