diff --git a/src/query/inc/tsqlfunction.h b/src/query/inc/tsqlfunction.h
index c314087179763f9b745c2fa4a4c318c061c72102..a78bb7ec51de2886d5396a9a18192947221bce88 100644
--- a/src/query/inc/tsqlfunction.h
+++ b/src/query/inc/tsqlfunction.h
@@ -177,7 +177,7 @@ typedef struct SQLFunctionCtx {
   int16_t      outputType;
   int16_t      outputBytes;  // size of results, determined by function and input column data type
   bool         hasNull;      // null value exist in current block
-  bool         requireNull;    // require null in some function
+  bool         requireNull;  // require null in some function
   int16_t      functionId;   // function id
   void *       aInputElemBuf;
   char *       aOutputBuf;            // final result output buffer, point to sdata->data
diff --git a/src/query/src/qExecutor.c b/src/query/src/qExecutor.c
index 75614578feb81f4a218d6f9a850d5f414c773290..511d6c36efdfb0a74c0265ebaba533d854a41a23 100644
--- a/src/query/src/qExecutor.c
+++ b/src/query/src/qExecutor.c
@@ -743,9 +743,9 @@ static int32_t getNumOfRowsInTimeWindow(SQuery *pQuery, SDataBlockInfo *pDataBlo
                                         int32_t startPos, TSKEY ekey, __block_search_fn_t searchFn, bool updateLastKey) {
   assert(startPos >= 0 && startPos < pDataBlockInfo->rows);
 
-  int32_t num = -1;
+  int32_t num   = -1;
   int32_t order = pQuery->order.order;
-  int32_t step = GET_FORWARD_DIRECTION_FACTOR(order);
+  int32_t step  = GET_FORWARD_DIRECTION_FACTOR(order);
 
   STableQueryInfo* item = pQuery->current;
 
@@ -779,27 +779,24 @@ static int32_t getNumOfRowsInTimeWindow(SQuery *pQuery, SDataBlockInfo *pDataBlo
   return num;
 }
 
-static void doBlockwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, bool closed, STimeWindow *pWin,
-                                      int32_t offset, int32_t forwardStep, TSKEY *tsBuf, int32_t numOfTotal) {
+static void doBlockwiseApplyFunctions(SQueryRuntimeEnv *pRuntimeEnv, bool closed, STimeWindow *pWin, int32_t offset,
+                                      int32_t forwardStep, TSKEY *tsCol, int32_t numOfTotal) {
   SQuery *        pQuery = pRuntimeEnv->pQuery;
   SQLFunctionCtx *pCtx = pRuntimeEnv->pCtx;
 
   if (IS_MASTER_SCAN(pRuntimeEnv) || closed) {
     for (int32_t k = 0; k < pQuery->numOfOutput; ++k) {
-      int32_t functionId = pQuery->pSelectExpr[k].base.functionId;
-
       pCtx[k].nStartQueryTimestamp = pWin->skey;
       pCtx[k].size = forwardStep;
       pCtx[k].startOffset = (QUERY_IS_ASC_QUERY(pQuery)) ? offset : offset - (forwardStep - 1);
 
+      int32_t functionId = pQuery->pSelectExpr[k].base.functionId;
       if ((aAggs[functionId].nStatus & TSDB_FUNCSTATE_SELECTIVITY) != 0) {
-        pCtx[k].ptsList = &tsBuf[pCtx[k].startOffset];
+        pCtx[k].ptsList = &tsCol[pCtx[k].startOffset];
       }
 
       // not a whole block involved in query processing, statistics data can not be used
-      if (forwardStep != numOfTotal) {
-        pCtx[k].preAggVals.isSet = false;
-      }
+      pCtx[k].preAggVals.isSet = (forwardStep == numOfTotal);
 
       if (functionNeedToExecute(pRuntimeEnv, &pCtx[k], functionId)) {
         aAggs[functionId].xFunction(&pCtx[k]);
@@ -924,19 +921,11 @@ static char *getDataBlock(SQueryRuntimeEnv *pRuntimeEnv, SArithmeticSupport *sas
 
   char *dataBlock = NULL;
   SQuery *pQuery = pRuntimeEnv->pQuery;
-  SQLFunctionCtx *pCtx = pRuntimeEnv->pCtx;
 
   int32_t functionId = pQuery->pSelectExpr[col].base.functionId;
   if (functionId == TSDB_FUNC_ARITHM) {
     sas->pArithExpr = &pQuery->pSelectExpr[col];
 
-    // set the start offset to be the lowest start position, no matter asc/desc query order
-    if (QUERY_IS_ASC_QUERY(pQuery)) {
-      pCtx->startOffset = pQuery->pos;
-    } else {
-      pCtx->startOffset = pQuery->pos - (size - 1);
-    }
-
     sas->offset  = 0;
     sas->colList = pQuery->colList;
     sas->numOfCols = pQuery->numOfCols;
@@ -1478,7 +1467,8 @@ void setExecParams(SQuery *pQuery, SQLFunctionCtx *pCtx, void* inputData, TSKEY
   pCtx->size = QUERY_IS_ASC_QUERY(pQuery) ? pBlockInfo->rows - pQuery->pos : pQuery->pos + 1;
 
   // minimum value no matter ascending/descending order query
-  pCtx->startOffset = QUERY_IS_ASC_QUERY(pQuery) ? pQuery->pos: (pQuery->pos - pCtx->size - 1);
+  pCtx->startOffset = QUERY_IS_ASC_QUERY(pQuery) ? pQuery->pos: (pQuery->pos - pCtx->size + 1);
+  assert(pCtx->startOffset >= 0);
 
   uint32_t status = aAggs[functionId].nStatus;
   if (((status & (TSDB_FUNCSTATE_SELECTIVITY | TSDB_FUNCSTATE_NEED_TS)) != 0) && (tsCol != NULL)) {