diff --git a/src/client/src/tscSubquery.c b/src/client/src/tscSubquery.c
index ca778d4f920c3de608ce01e1081357c3b4ff930a..e5d7f030076ab8aea6041cbde0917a2c708b12cc 100644
--- a/src/client/src/tscSubquery.c
+++ b/src/client/src/tscSubquery.c
@@ -761,9 +761,7 @@ static void tsCompRetrieveCallback(void* param, TAOS_RES* tres, int32_t numOfRow
       pSupporter->pTSBuf = pBuf;
     } else {
       assert(pQueryInfo->numOfTables == 1);  // for subquery, only one
-      STableMetaInfo* pTableMetaInfo = tscGetMetaInfo(pQueryInfo, 0);
-
-      tsBufMerge(pSupporter->pTSBuf, pBuf, pTableMetaInfo->vgroupIndex);
+      tsBufMerge(pSupporter->pTSBuf, pBuf);
       tsBufDestroy(pBuf);
     }
 
diff --git a/src/query/inc/qTsbuf.h b/src/query/inc/qTsbuf.h
index be3d97dad763a95463dba2c6d7eb7e3c16c7c330..8bd775dac5b669ac74244842e6844380f1a23a4a 100644
--- a/src/query/inc/qTsbuf.h
+++ b/src/query/inc/qTsbuf.h
@@ -111,7 +111,7 @@ STSBuf* tsBufCreateFromCompBlocks(const char* pData, int32_t numOfBlocks, int32_
 void* tsBufDestroy(STSBuf* pTSBuf);
 
 void    tsBufAppend(STSBuf* pTSBuf, int32_t vnodeId, tVariant* tag, const char* pData, int32_t len);
-int32_t tsBufMerge(STSBuf* pDestBuf, const STSBuf* pSrcBuf, int32_t vnodeIdx);
+int32_t tsBufMerge(STSBuf* pDestBuf, const STSBuf* pSrcBuf);
 
 STSBuf* tsBufClone(STSBuf* pTSBuf);
 
diff --git a/src/query/src/qTsbuf.c b/src/query/src/qTsbuf.c
index 95fd88f1d89a2bd8253abc286e2787b9f0fb74cb..7c2f8ebb5eb598205eb0c8b9f48c10c80a687bfb 100644
--- a/src/query/src/qTsbuf.c
+++ b/src/query/src/qTsbuf.c
@@ -715,7 +715,7 @@ STSElem tsBufGetElem(STSBuf* pTSBuf) {
  * @param vnodeId
  * @return
  */
-int32_t tsBufMerge(STSBuf* pDestBuf, const STSBuf* pSrcBuf, int32_t vnodeId) {
+int32_t tsBufMerge(STSBuf* pDestBuf, const STSBuf* pSrcBuf) {
   if (pDestBuf == NULL || pSrcBuf == NULL || pSrcBuf->numOfVnodes <= 0) {
     return 0;
   }
@@ -725,14 +725,13 @@ int32_t tsBufMerge(STSBuf* pDestBuf, const STSBuf* pSrcBuf, int32_t vnodeId) {
   }
   
   // src can only have one vnode index
-  if (pSrcBuf->numOfVnodes > 1) {
-    return -1;
-  }
-  
+  assert(pSrcBuf->numOfVnodes == 1);
+
   // there are data in buffer, flush to disk first
   tsBufFlush(pDestBuf);
   
   // compared with the last vnode id
+  int32_t vnodeId = tsBufGetLastVnodeInfo((STSBuf*) pSrcBuf)->info.vnode;
   if (vnodeId != tsBufGetLastVnodeInfo(pDestBuf)->info.vnode) {
     int32_t oldSize = pDestBuf->numOfVnodes;
     int32_t newSize = oldSize + pSrcBuf->numOfVnodes;
diff --git a/src/query/tests/tsBufTest.cpp b/src/query/tests/tsBufTest.cpp
index b78c5314f243874e348748a6434d224592489528..f22f61e8904b2f964915c59b55d19bcf211b7640 100644
--- a/src/query/tests/tsBufTest.cpp
+++ b/src/query/tests/tsBufTest.cpp
@@ -416,8 +416,8 @@ void mergeDiffVnodeBufferTest() {
     int64_t* list = createTsList(num, start, step);
     t.i64Key = i;
 
-    tsBufAppend(pTSBuf1, 0, &t, (const char*)list, num * sizeof(int64_t));
-    tsBufAppend(pTSBuf2, 0, &t, (const char*)list, num * sizeof(int64_t));
+    tsBufAppend(pTSBuf1, 1, &t, (const char*)list, num * sizeof(int64_t));
+    tsBufAppend(pTSBuf2, 9, &t, (const char*)list, num * sizeof(int64_t));
 
     free(list);
 
@@ -426,7 +426,7 @@ void mergeDiffVnodeBufferTest() {
 
   tsBufFlush(pTSBuf2);
 
-  tsBufMerge(pTSBuf1, pTSBuf2, 9);
+  tsBufMerge(pTSBuf1, pTSBuf2);
   EXPECT_EQ(pTSBuf1->numOfVnodes, 2);
   EXPECT_EQ(pTSBuf1->numOfTotal, numOfTags * 2 * num);
 
@@ -459,8 +459,6 @@ void mergeIdenticalVnodeBufferTest() {
     start += step * num;
   }
 
-
-
   for (int32_t i = numOfTags; i < numOfTags * 2; ++i) {
     int64_t* list = createTsList(num, start, step);
 
@@ -473,7 +471,7 @@ void mergeIdenticalVnodeBufferTest() {
 
   tsBufFlush(pTSBuf2);
 
-  tsBufMerge(pTSBuf1, pTSBuf2, 12);
+  tsBufMerge(pTSBuf1, pTSBuf2);
   EXPECT_EQ(pTSBuf1->numOfVnodes, 1);
   EXPECT_EQ(pTSBuf1->numOfTotal, numOfTags * 2 * num);