diff --git a/src/client/inc/tsclient.h b/src/client/inc/tsclient.h
index e538281bc06c8470e638f7b51ef7689e0a41eef7..bd956aeb7426f145de33ccc82ea65c56157ed919 100644
--- a/src/client/inc/tsclient.h
+++ b/src/client/inc/tsclient.h
@@ -294,11 +294,12 @@ typedef struct STscObj {
 } STscObj;
 
 typedef struct SSqlObj {
-  void *   signature;
-  STscObj *pTscObj;
-  void (*fp)();
-  void (*fetchFp)();
-  void *           param;
+  void            *signature;
+  STscObj         *pTscObj;
+  void            *SRpcReqContext;
+  void            (*fp)();
+  void            (*fetchFp)();
+  void            *param;
   int64_t          stime;
   uint32_t         queryId;
   void *           pStream;
diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index b509dd33640a820835a63a590d2a2370e8561ee2..e15a5e618ad0dbd3aac1751fa543c50692443f6c 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -196,8 +196,8 @@ int tscSendMsgToServer(SSqlObj *pSql) {
       .handle  = pSql,
       .code    = 0
   };
-  rpcSendRequest(pObj->pDnodeConn, &pSql->ipList, &rpcMsg);
 
+  pSql->SRpcReqContext = rpcSendRequest(pObj->pDnodeConn, &pSql->ipList, &rpcMsg);
   return TSDB_CODE_SUCCESS;
 }
 
@@ -422,7 +422,7 @@ void tscKillSTableQuery(SSqlObj *pSql) {
      * sub-queries not correctly released and master sql object of super table query reaches an abnormal state.
      */
     pSql->pSubs[i]->res.code = TSDB_CODE_TSC_QUERY_CANCELLED;
-//    taosStopRpcConn(pSql->pSubs[i]->);
+    rpcCancelRequest(pSql->pSubs[i]->SRpcReqContext);
   }
 
   /*
diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index b13e7b7ccfb50a93806ab055897f7b1b49e61b17..0be7db435d679eb3ce8452975c59f754fd2e5cbf 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -627,7 +627,7 @@ void taos_stop_query(TAOS_RES *res) {
     return;
   }
 
-  //taosStopRpcConn(pSql->thandle);
+  rpcCancelRequest(pSql->SRpcReqContext);
   tscTrace("%p query is cancelled", res);
 }
 
diff --git a/src/inc/trpc.h b/src/inc/trpc.h
index 6c5d7fa889b855b91fb47e99e1bf5a80bc88f99e..30e0f9eee1889e8b832812fcc3f17f81c157724e 100644
--- a/src/inc/trpc.h
+++ b/src/inc/trpc.h
@@ -84,7 +84,7 @@ void  rpcSendRedirectRsp(void *pConn, const SRpcIpSet *pIpSet);
 int   rpcGetConnInfo(void *thandle, SRpcConnInfo *pInfo);
 void  rpcSendRecv(void *shandle, SRpcIpSet *pIpSet, const SRpcMsg *pReq, SRpcMsg *pRsp);
 int   rpcReportProgress(void *pConn, char *pCont, int contLen);
-void  rpcCanelRequest(void *pContext);
+void  rpcCancelRequest(void *pContext);
 
 #ifdef __cplusplus
 }
diff --git a/src/tsdb/src/tsdbRead.c b/src/tsdb/src/tsdbRead.c
index 9ac47ef22b6778051ba446db40d91a57aaead9f2..46ed3eaf844478c69affc8e53a565b9a473aead6 100644
--- a/src/tsdb/src/tsdbRead.c
+++ b/src/tsdb/src/tsdbRead.c
@@ -792,38 +792,77 @@ static int32_t copyDataFromFileBlock(STsdbQueryHandle* pQueryHandle, int32_t cap
   int32_t requiredNumOfCols = taosArrayGetSize(pQueryHandle->pColumns);
   
   //data in buffer has greater timestamp, copy data in file block
-  for (int32_t i = 0; i < requiredNumOfCols; ++i) {
+  int32_t i = 0, j = 0;
+  while(i < requiredNumOfCols && j < pCols->numOfCols) {
     SColumnInfoData* pColInfo = taosArrayGet(pQueryHandle->pColumns, i);
-    int32_t          bytes = pColInfo->info.bytes;
-    
+
+    SDataCol* src = &pCols->cols[j];
+    if (src->colId < pColInfo->info.colId) {
+      j++;
+      continue;
+    }
+
+    int32_t bytes = pColInfo->info.bytes;
+
     if (ASCENDING_TRAVERSE(pQueryHandle->order)) {
       pData = pColInfo->pData + numOfRows * pColInfo->info.bytes;
     } else {
       pData = pColInfo->pData + (capacity - numOfRows - num) * pColInfo->info.bytes;
     }
-    
-    for (int32_t j = 0; j < pCols->numOfCols; ++j) {  // todo opt performance
-      SDataCol* src = &pCols->cols[j];
-      
-      if (pColInfo->info.colId == src->colId) {
-        
-        if (pColInfo->info.type != TSDB_DATA_TYPE_BINARY && pColInfo->info.type != TSDB_DATA_TYPE_NCHAR) {
-          memmove(pData, src->pData + bytes * start, bytes * num);
-        } else {  // handle the var-string
-          char* dst = pData;
-          
-          // todo refactor, only copy one-by-one
-          for (int32_t k = start; k < num + start; ++k) {
-            char* p = tdGetColDataOfRow(src, k);
-            memcpy(dst, p, varDataTLen(p));
-            dst += bytes;
-          }
+
+    if (pColInfo->info.colId == src->colId) {
+
+      if (pColInfo->info.type != TSDB_DATA_TYPE_BINARY && pColInfo->info.type != TSDB_DATA_TYPE_NCHAR) {
+        memmove(pData, src->pData + bytes * start, bytes * num);
+      } else {  // handle the var-string
+        char* dst = pData;
+
+        // todo refactor, only copy one-by-one
+        for (int32_t k = start; k < num + start; ++k) {
+          char* p = tdGetColDataOfRow(src, k);
+          memcpy(dst, p, varDataTLen(p));
+          dst += bytes;
         }
-        
-        break;
       }
+
+      j++;
+      i++;
+    } else { // pColInfo->info.colId < src->colId, it is a NULL data
+      if (pColInfo->info.type == TSDB_DATA_TYPE_BINARY || pColInfo->info.type == TSDB_DATA_TYPE_NCHAR) {
+        char* dst = pData;
+
+        for(int32_t k = start; k < num + start; ++k) {
+          setVardataNull(dst, pColInfo->info.type);
+          dst += bytes;
+        }
+      } else {
+        setNullN(pData, pColInfo->info.type, pColInfo->info.bytes, num);
+      }
+      i++;
     }
   }
+
+  while (i < requiredNumOfCols) { // the remain columns are all null data
+    SColumnInfoData* pColInfo = taosArrayGet(pQueryHandle->pColumns, i);
+    if (ASCENDING_TRAVERSE(pQueryHandle->order)) {
+      pData = pColInfo->pData + numOfRows * pColInfo->info.bytes;
+    } else {
+      pData = pColInfo->pData + (capacity - numOfRows - num) * pColInfo->info.bytes;
+    }
+
+    if (pColInfo->info.type == TSDB_DATA_TYPE_BINARY || pColInfo->info.type == TSDB_DATA_TYPE_NCHAR) {
+      char* dst = pData;
+
+      for(int32_t k = start; k < num + start; ++k) {
+        setVardataNull(dst, pColInfo->info.type);
+        dst += pColInfo->info.bytes;
+      }
+    } else {
+      setNullN(pData, pColInfo->info.type, pColInfo->info.bytes, num);
+    }
+
+    i++;
+  }
   
   pQueryHandle->cur.win.ekey = tsArray[end];
   pQueryHandle->cur.lastKey = tsArray[end] + step;