diff --git a/source/dnode/vnode/src/tsdb/tsdbCache.c b/source/dnode/vnode/src/tsdb/tsdbCache.c
index 5a1ddf811d851ffabad7336c61707830d5d21385..1360a272cca8c5a7aa926ecd5af61a11e6fc4a8a 100644
--- a/source/dnode/vnode/src/tsdb/tsdbCache.c
+++ b/source/dnode/vnode/src/tsdb/tsdbCache.c
@@ -159,7 +159,11 @@ SLastCol *tsdbCacheDeserialize(char const *value) {
   SLastCol *pLastCol = (SLastCol *)value;
   SColVal  *pColVal = &pLastCol->colVal;
   if (IS_VAR_DATA_TYPE(pColVal->type)) {
-    pColVal->value.pData = (char *)value + sizeof(*pLastCol);
+    if (pColVal->value.nData > 0) {
+      pColVal->value.pData = (char *)value + sizeof(*pLastCol);
+    } else {
+      pColVal->value.pData = NULL;
+    }
   }
 
   return pLastCol;
@@ -177,8 +181,10 @@ void tsdbCacheSerialize(SLastCol *pLastCol, char **value, size_t *size) {
   if (IS_VAR_DATA_TYPE(pColVal->type)) {
     uint8_t *pVal = pColVal->value.pData;
     pColVal->value.pData = *value + sizeof(*pLastCol);
-    if (pColVal->value.nData) {
+    if (pColVal->value.nData > 0) {
       memcpy(pColVal->value.pData, pVal, pColVal->value.nData);
+    } else {
+      pColVal->value.pData = NULL;
     }
   }
   *size = length;
diff --git a/source/dnode/vnode/src/tsdb/tsdbCacheRead.c b/source/dnode/vnode/src/tsdb/tsdbCacheRead.c
index 0e03e6e5fb98d319d1bccf2e321f9b2335c03af4..0d47940582a9fed54eee0104746c52965f44c0b8 100644
--- a/source/dnode/vnode/src/tsdb/tsdbCacheRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbCacheRead.c
@@ -208,7 +208,7 @@ void* tsdbCacherowsReaderClose(void* pReader) {
 
 static void freeItem(void* pItem) {
   SLastCol* pCol = (SLastCol*)pItem;
-  if (IS_VAR_DATA_TYPE(pCol->colVal.type)) {
+  if (IS_VAR_DATA_TYPE(pCol->colVal.type) && pCol->colVal.value.pData) {
     taosMemoryFree(pCol->colVal.value.pData);
   }
 }