diff --git a/src/common/src/tdataformat.c b/src/common/src/tdataformat.c
index bd082db16c4dab6db04ea4f322b8ceccb21b58e7..cf1b77d12ce671d3d0f31bc9c4a1c8a535bc6113 100644
--- a/src/common/src/tdataformat.c
+++ b/src/common/src/tdataformat.c
@@ -427,27 +427,25 @@ void tdMergeTwoDataCols(SDataCols *target, SDataCols *src1, int *iter1, SDataCol
     TSKEY key1 = (*iter1 >= src1->numOfPoints) ? INT64_MAX : ((TSKEY *)(src1->cols[0].pData))[*iter1];
     TSKEY key2 = (*iter2 >= src2->numOfPoints) ? INT64_MAX : ((TSKEY *)(src2->cols[0].pData))[*iter2];
 
-    if (key1 < key2) {
+    if (key1 <= key2) {
       for (int i = 0; i < src1->numOfCols; i++) {
         ASSERT(target->cols[i].type == src1->cols[i].type);
-        dataColAppendVal(target->cols[i].pData, tdGetColDataOfRow(src1->cols + i, *iter1), target->numOfPoints,
+        dataColAppendVal(&(target->cols[i]), tdGetColDataOfRow(src1->cols + i, *iter1), target->numOfPoints,
                          target->maxPoints);
       }
 
       target->numOfPoints++;
       (*iter1)++;
-    } else if (key1 > key2) {
+      if (key1 == key2) (*iter2)++;
+    } else {
       for (int i = 0; i < src2->numOfCols; i++) {
         ASSERT(target->cols[i].type == src2->cols[i].type);
-        dataColAppendVal(target->cols[i].pData, tdGetColDataOfRow(src2->cols + i, *iter2), target->numOfPoints,
+        dataColAppendVal(&(target->cols[i]), tdGetColDataOfRow(src2->cols + i, *iter2), target->numOfPoints,
                          target->maxPoints);
       }
 
       target->numOfPoints++;
       (*iter2)++;
-    } else {
-      // TODO: deal with duplicate keys
-      ASSERT(false);
     }
   }
 }
\ No newline at end of file
diff --git a/src/tsdb/inc/tsdbMain.h b/src/tsdb/inc/tsdbMain.h
index 8a0a9e1208b7fb45994be95200a3f2a2a0ceb4ff..7779dd547935a7f0d4f275b156ed7925181cb768 100644
--- a/src/tsdb/inc/tsdbMain.h
+++ b/src/tsdb/inc/tsdbMain.h
@@ -500,6 +500,7 @@ int tsdbLoadCompInfo(SRWHelper *pHelper, void *target);
 int tsdbLoadCompData(SRWHelper *pHelper, SCompBlock *pCompBlock, void *target);
 int tsdbLoadBlockDataCols(SRWHelper *pHelper, SDataCols *pDataCols, int blkIdx, int16_t *colIds, int numOfColIds);
 int tsdbLoadBlockData(SRWHelper *pHelper, SCompBlock *pCompBlock, SDataCols *target);
+// void tsdbGetDataStatis(SRWHelper *pHelper, SDataStatis *pStatis, int numOfCols);
 
 // --------- For write operations
 int tsdbWriteDataBlock(SRWHelper *pHelper, SDataCols *pDataCols);