diff --git a/src/query/src/qAggMain.c b/src/query/src/qAggMain.c
index b02b8e8484f5371edd3608e5a145b7b0f51d9276..7d925631f62bf648c5f4d58fffdd22264324c605 100644
--- a/src/query/src/qAggMain.c
+++ b/src/query/src/qAggMain.c
@@ -5199,8 +5199,12 @@ static bool unique_function_setup(SQLFunctionCtx *pCtx, SResultRowCellInfo* pRes
   return true;
 }
 
-static void do_unique_function(SQLFunctionCtx *pCtx, SUniqueFuncInfo *pInfo, TSKEY timestamp, char *pData, char *tag, int32_t bytes){
-  UniqueUnit **unique = taosHashGet(*pCtx->pUniqueSet, pData, bytes);
+static void do_unique_function(SQLFunctionCtx *pCtx, SUniqueFuncInfo *pInfo, TSKEY timestamp, char *pData, char *tag, int32_t bytes, int16_t type){
+  int32_t hashKeyBytes = bytes;
+  if(IS_VAR_DATA_TYPE(type)){
+    hashKeyBytes = varDataTLen(pData);
+  }
+  UniqueUnit **unique = taosHashGet(*pCtx->pUniqueSet, pData, hashKeyBytes);
   if (unique == NULL) {
     size_t size = sizeof(UniqueUnit) + bytes + pCtx->tagInfo.tagsLen;
     char *tmp = pInfo->res + pInfo->num * size;
@@ -5226,7 +5230,7 @@ static void do_unique_function(SQLFunctionCtx *pCtx, SUniqueFuncInfo *pInfo, TSK
       }
     }
 
-    taosHashPut(*pCtx->pUniqueSet, pData, bytes, &tmp, sizeof(UniqueUnit*));
+    taosHashPut(*pCtx->pUniqueSet, pData, hashKeyBytes, &tmp, sizeof(UniqueUnit*));
     pInfo->num++;
   }else if((*unique)->timestamp > timestamp){
     (*unique)->timestamp = timestamp;
@@ -5242,7 +5246,7 @@ static void unique_function(SQLFunctionCtx *pCtx) {
     if (pCtx->ptsList != NULL) {
       k = GET_TS_DATA(pCtx, i);
     }
-    do_unique_function(pCtx, pInfo, k, pData, NULL, pCtx->inputBytes);
+    do_unique_function(pCtx, pInfo, k, pData, NULL, pCtx->inputBytes, pCtx->inputType);
 
     if (sizeof(SUniqueFuncInfo) + pInfo->num * (sizeof(UniqueUnit) + pCtx->inputBytes + pCtx->tagInfo.tagsLen) >= MAX_UNIQUE_RESULT_SIZE){
       GET_RES_INFO(pCtx)->numOfRes = -1;    // mark out of memory
@@ -5262,7 +5266,7 @@ static void unique_function_merge(SQLFunctionCtx *pCtx) {
     TSKEY timestamp = ((UniqueUnit*)tmp)->timestamp;
     char *data = tmp + sizeof(UniqueUnit);
     char *tags = tmp + sizeof(UniqueUnit) + pCtx->outputBytes;
-    do_unique_function(pCtx, pOutput, timestamp, data, tags, pCtx->outputBytes);
+    do_unique_function(pCtx, pOutput, timestamp, data, tags, pCtx->outputBytes, pCtx->outputType);
 
     if (sizeof(SUniqueFuncInfo) + pOutput->num * (sizeof(UniqueUnit) + pCtx->outputBytes + pCtx->tagInfo.tagsLen) >= MAX_UNIQUE_RESULT_SIZE){
       GET_RES_INFO(pCtx)->numOfRes = -1;    // mark out of memory
diff --git a/src/tsdb/src/tsdbRead.c b/src/tsdb/src/tsdbRead.c
index af81bea38d95943dc1c413bd7087d3eea598c6c4..e185db215732ac3d3ea9d62be042b265b018335d 100644
--- a/src/tsdb/src/tsdbRead.c
+++ b/src/tsdb/src/tsdbRead.c
@@ -1759,7 +1759,6 @@ static int32_t doCopyRowsFromFileBlock(STsdbQueryHandle* pQueryHandle, int32_t c
         // todo refactor, only copy one-by-one
         for (int32_t k = start; k < num + start; ++k) {
           const char* p = tdGetColDataOfRow(src, k);
-          memset(dst, 0, bytes);
           memcpy(dst, p, varDataTLen(p));
           dst += bytes;
         }
@@ -1772,7 +1771,6 @@ static int32_t doCopyRowsFromFileBlock(STsdbQueryHandle* pQueryHandle, int32_t c
         char* dst = pData;
 
         for(int32_t k = start; k < num + start; ++k) {
-          memset(dst, 0, bytes);
           setVardataNull(dst, pColInfo->info.type);
           dst += bytes;
         }
@@ -1795,7 +1793,6 @@ static int32_t doCopyRowsFromFileBlock(STsdbQueryHandle* pQueryHandle, int32_t c
       char* dst = pData;
 
       for(int32_t k = start; k < num + start; ++k) {
-        memset(pData, 0, pColInfo->info.bytes);
         setVardataNull(dst, pColInfo->info.type);
         dst += pColInfo->info.bytes;
       }
@@ -1863,7 +1860,6 @@ static void mergeTwoRowFromMem(STsdbQueryHandle* pQueryHandle, int32_t capacity,
     } else {
       pData = (char*)pColInfo->pData + (capacity - numOfRows - 1) * pColInfo->info.bytes;
     }
-    memset(pData, 0, pColInfo->info.bytes);
 
     int32_t colIdOfRow1;
     if(j >= numOfColsOfRow1) {
@@ -1999,7 +1995,6 @@ static void mergeTwoRowFromMem(STsdbQueryHandle* pQueryHandle, int32_t capacity,
       } else {
         pData = (char*)pColInfo->pData + (capacity - numOfRows - 1) * pColInfo->info.bytes;
       }
-      memset(pData, 0, pColInfo->info.bytes);
 
       if (pColInfo->info.type == TSDB_DATA_TYPE_BINARY || pColInfo->info.type == TSDB_DATA_TYPE_NCHAR) {
         setVardataNull(pData, pColInfo->info.type);
@@ -3155,8 +3150,7 @@ static bool loadCachedLast(STsdbQueryHandle* pQueryHandle) {
       }
     
       pData = (char*)pColInfo->pData + numOfRows * pColInfo->info.bytes;
-      memset(pData, 0, pColInfo->info.bytes);
-      if (pTable->lastCols[j].bytes > 0) {        
+      if (pTable->lastCols[j].bytes > 0) {
         void* value = pTable->lastCols[j].pData;
         switch (pColInfo->info.type) {
           case TSDB_DATA_TYPE_BINARY:
@@ -3210,7 +3204,6 @@ static bool loadCachedLast(STsdbQueryHandle* pQueryHandle) {
 
           pColInfo = taosArrayGet(pQueryHandle->pColumns, n);
           pData = (char*)pColInfo->pData + numOfRows * pColInfo->info.bytes;;
-          memset(pData, 0, pColInfo->info.bytes);
           if (pColInfo->info.colId == PRIMARYKEY_TIMESTAMP_COL_INDEX) {
             *(TSKEY *)pData = pTable->lastCols[j].ts;
             continue;
@@ -3236,7 +3229,6 @@ static bool loadCachedLast(STsdbQueryHandle* pQueryHandle) {
     if (priKey != TSKEY_INITIAL_VAL) {
       pColInfo = taosArrayGet(pQueryHandle->pColumns, priIdx);
       pData = (char*)pColInfo->pData + numOfRows * pColInfo->info.bytes;
-      memset(pData, 0, pColInfo->info.bytes);
 
       *(TSKEY *)pData = priKey;
 
@@ -3247,7 +3239,6 @@ static bool loadCachedLast(STsdbQueryHandle* pQueryHandle) {
       
         pColInfo = taosArrayGet(pQueryHandle->pColumns, n);
         pData = (char*)pColInfo->pData + numOfRows * pColInfo->info.bytes;;
-        memset(pData, 0, pColInfo->info.bytes);
 
         assert (pColInfo->info.colId != PRIMARYKEY_TIMESTAMP_COL_INDEX);