diff --git a/source/libs/executor/inc/tsort.h b/source/libs/executor/inc/tsort.h
index c8b1b3ee513bc508de5187c8d39ace4ae5e4b7f8..fd3581e2bfa86d9761eae6448ad249f178c96f15 100644
--- a/source/libs/executor/inc/tsort.h
+++ b/source/libs/executor/inc/tsort.h
@@ -130,6 +130,12 @@ bool tsortIsNullVal(STupleHandle* pVHandle, int32_t colId);
  */
 void* tsortGetValue(STupleHandle* pVHandle, int32_t colId);
 
+/**
+ *
+ * @param pVHandle
+ * @return
+ */
+uint64_t tsortGetGroupId(STupleHandle* pVHandle);
 /**
  *
  * @param pSortHandle
diff --git a/source/libs/executor/src/sortoperator.c b/source/libs/executor/src/sortoperator.c
index 3034f409f7b0cd840dd6eeb3ffeabb8598e961b6..95f9514b0778d26b0933628d16aa7da891abee23 100644
--- a/source/libs/executor/src/sortoperator.c
+++ b/source/libs/executor/src/sortoperator.c
@@ -231,6 +231,10 @@ typedef struct SMultiwaySortMergeOperatorInfo {
 
   SSDataBlock* pInputBlock;
   int64_t startTs;  // sort start time
+
+  bool  hasGroupId;
+  uint64_t groupId;
+  STupleHandle *prefetchedTuple;
 } SMultiwaySortMergeOperatorInfo;
 
 int32_t doOpenMultiwaySortMergeOperator(SOperatorInfo* pOperator) {
@@ -269,6 +273,70 @@ int32_t doOpenMultiwaySortMergeOperator(SOperatorInfo* pOperator) {
   return TSDB_CODE_SUCCESS;
 }
 
+SSDataBlock* getMultiwaySortedBlockData(SSortHandle* pHandle, SSDataBlock* pDataBlock, int32_t capacity,
+                                SArray* pColMatchInfo, SMultiwaySortMergeOperatorInfo* pInfo) {
+  blockDataCleanup(pDataBlock);
+
+  SSDataBlock* p = tsortGetSortedDataBlock(pHandle);
+  if (p == NULL) {
+    return NULL;
+  }
+
+  blockDataEnsureCapacity(p, capacity);
+
+  while (1) {
+
+    STupleHandle* pTupleHandle = NULL;
+    if (pInfo->prefetchedTuple == NULL) {
+      pTupleHandle = tsortNextTuple(pHandle);
+    } else {
+      pTupleHandle = pInfo->prefetchedTuple;
+      pInfo->prefetchedTuple = NULL;
+    }
+
+    if (pTupleHandle == NULL) {
+      break;
+    }
+
+    uint64_t tupleGroupId = tsortGetGroupId(pTupleHandle);
+    if (!pInfo->hasGroupId) {
+      pInfo->groupId = tupleGroupId;
+      pInfo->hasGroupId = true;
+      appendOneRowToDataBlock(p, pTupleHandle);
+    } else if (pInfo->groupId == tupleGroupId) {
+      appendOneRowToDataBlock(p, pTupleHandle);
+    } else {
+      pInfo->prefetchedTuple = pTupleHandle;
+      pInfo->groupId = tupleGroupId;
+      break;
+    }
+
+    if (p->info.rows >= capacity) {
+      break;
+    }
+
+  }
+
+  if (p->info.rows > 0) {
+    int32_t numOfCols = taosArrayGetSize(pColMatchInfo);
+    for (int32_t i = 0; i < numOfCols; ++i) {
+      SColMatchInfo* pmInfo = taosArrayGet(pColMatchInfo, i);
+      ASSERT(pmInfo->matchType == COL_MATCH_FROM_SLOT_ID);
+
+      SColumnInfoData* pSrc = taosArrayGet(p->pDataBlock, pmInfo->srcSlotId);
+      SColumnInfoData* pDst = taosArrayGet(pDataBlock->pDataBlock, pmInfo->targetSlotId);
+      colDataAssign(pDst, pSrc, p->info.rows);
+    }
+
+    pDataBlock->info.rows = p->info.rows;
+    pDataBlock->info.capacity = p->info.rows;
+  }
+
+  blockDataDestroy(p);
+  return (pDataBlock->info.rows > 0) ? pDataBlock : NULL;
+}
+
+
 SSDataBlock* doMultiwaySortMerge(SOperatorInfo* pOperator) {
   if (pOperator->status == OP_EXEC_DONE) {
     return NULL;
@@ -283,7 +351,11 @@ SSDataBlock* doMultiwaySortMerge(SOperatorInfo* pOperator) {
   }
 
   SSDataBlock* pBlock =
-      getSortedBlockData(pInfo->pSortHandle, pInfo->binfo.pRes, pOperator->resultInfo.capacity, pInfo->pColMatchInfo);
+      getMultiwaySortedBlockData(pInfo->pSortHandle,
+                         pInfo->binfo.pRes,
+                         pOperator->resultInfo.capacity,
+                         pInfo->pColMatchInfo,
+                                 pInfo);
 
   if (pBlock != NULL) {
     pOperator->resultInfo.totalRows += pBlock->info.rows;
diff --git a/source/libs/executor/src/tsort.c b/source/libs/executor/src/tsort.c
index 3705d0a57b2d83d87cba3f038244a011cb637fee..846da4a32a248a8eb4c4e91f0a0a0791df84facb 100644
--- a/source/libs/executor/src/tsort.c
+++ b/source/libs/executor/src/tsort.c
@@ -709,6 +709,10 @@ void* tsortGetValue(STupleHandle* pVHandle, int32_t colIndex) {
   return colDataGetData(pColInfo, pVHandle->rowIndex);
 }
 
+uint64_t tsortGetGroupId(STupleHandle* pVHandle) {
+  return pVHandle->pBlock->info.groupId;
+}
+
 SSortExecInfo tsortGetSortExecInfo(SSortHandle* pHandle) {
   SSortExecInfo info = {0};
 
diff --git a/tests/script/tsim/query/scalarNull.sim b/tests/script/tsim/query/scalarNull.sim
index b08ac1d3d9abe157915ec25c438d82e2774ced04..07bd5e57cd1d2c24e712a57c0f66aa4f764b8ccf 100644
--- a/tests/script/tsim/query/scalarNull.sim
+++ b/tests/script/tsim/query/scalarNull.sim
@@ -66,6 +66,7 @@ if $rows != 0 then
   return -1
 endi
 sql select * from tb1 where null;
+print $rows
 if $rows != 0 then
   return -1
 endi