diff --git a/source/common/src/tdatablock.c b/source/common/src/tdatablock.c
index dcea167e81766513423e93fe775f3816b4ca7716..cc7bcabee0c3cfa7e185dcc74d380e10812fa933 100644
--- a/source/common/src/tdatablock.c
+++ b/source/common/src/tdatablock.c
@@ -491,7 +491,12 @@ SSDataBlock* blockDataExtractBlock(SSDataBlock* pBlock, int32_t startIndex, int3
     SColumnInfoData* pDstCol = taosArrayGet(pDst->pDataBlock, i);
 
     for (int32_t j = startIndex; j < (startIndex + rowCount); ++j) {
-      bool  isNull = colDataIsNull(pColData, pBlock->info.rows, j, pBlock->pBlockAgg[i]);
+      bool isNull = false;
+      if (pBlock->pBlockAgg == NULL) {
+        isNull = colDataIsNull(pColData, pBlock->info.rows, j, NULL);
+      } else {
+        isNull = colDataIsNull(pColData, pBlock->info.rows, j, pBlock->pBlockAgg[i]);
+      }
       char* p = colDataGetData(pColData, j);
 
       colDataAppend(pDstCol, j - startIndex, p, isNull);