diff --git a/src/common/src/tdataformat.c b/src/common/src/tdataformat.c
index c34a049a417f5e9bd460cc167b0c08665fef4d49..29f9bc8854346e7596111969f251a2c85b6cde83 100644
--- a/src/common/src/tdataformat.c
+++ b/src/common/src/tdataformat.c
@@ -253,9 +253,10 @@ int dataColAppendVal(SDataCol *pCol, const void *value, int numOfRows, int maxPo
     }
 
     if(tdAllocMemForCol(pCol, maxPoints) < 0) return -1;
-    if (numOfRows > 0) {
+
+    if (((rowOffset == 0) && (numOfRows > 0)) || ((rowOffset == -1) && (numOfRows >= 0))) {
       // Find the first not null value, fill all previouse values as NULL
-      dataColSetNEleNull(pCol, numOfRows);
+      dataColSetNEleNull(pCol, numOfRows - rowOffset);
     }
   }