diff --git a/src/client/src/tscGlobalmerge.c b/src/client/src/tscGlobalmerge.c
index 0469b556874ce59d6c87e8237fcedf197766feeb..d01e1fcae3b4824959dced85f31b3cc252cda6c5 100644
--- a/src/client/src/tscGlobalmerge.c
+++ b/src/client/src/tscGlobalmerge.c
@@ -440,6 +440,15 @@ int32_t tscCreateGlobalMergerEnv(SQueryInfo *pQueryInfo, tExtMemBuffer ***pMemBu
     rlen += pExpr->base.resBytes;
   }
 
+  int32_t pg = DEFAULT_PAGE_SIZE;
+  int32_t overhead = sizeof(tFilePage);
+  while((pg - overhead) < rlen * 2) {
+    pg *= 2;
+  }
+
+  if (*nBufferSizes < pg){
+    *nBufferSizes = 2 * pg;
+  }
   int32_t capacity = 0;
   if (rlen != 0) {
     if ((*nBufferSizes) < rlen) {
@@ -454,12 +463,6 @@ int32_t tscCreateGlobalMergerEnv(SQueryInfo *pQueryInfo, tExtMemBuffer ***pMemBu
     return TSDB_CODE_TSC_OUT_OF_MEMORY;
   }
 
-  int32_t pg = DEFAULT_PAGE_SIZE;
-  int32_t overhead = sizeof(tFilePage);
-  while((pg - overhead) < rlen * 2) {
-    pg *= 2;
-  }
-
   assert(numOfSub <= pTableMetaInfo->vgroupList->numOfVgroups);
   for (int32_t i = 0; i < numOfSub; ++i) {
     (*pMemBuffer)[i] = createExtMemBuffer(*nBufferSizes, rlen, pg, pModel);
diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index e67dd7e14b6ae7c2032ba459242e2ce3db9b1cbb..01cee60f209853af709b5469b4a0f68b4e31225c 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -4938,7 +4938,11 @@ static int32_t createGlobalAggregateExpr(SQueryAttr* pQueryAttr, SQueryInfo* pQu
     pse->colInfo.colIndex = i;
 
     pse->colType = pExpr->base.resType;
-    pse->colBytes = pExpr->base.resBytes;
+    if(pExpr->base.resBytes > INT16_MAX && pExpr->base.functionId == TSDB_FUNC_UNIQUE){
+      pQueryAttr->interBytesForGlobal = pExpr->base.resBytes;
+    }else{
+      pse->colBytes = pExpr->base.resBytes;
+    }
   }
 
   {
diff --git a/src/common/inc/tname.h b/src/common/inc/tname.h
index 7a401d8a7f71c094654d06a2ed37ae3fd7fc9c94..e6b7dd1463a754bfaa78bb1081e3b6b0b753d752 100644
--- a/src/common/inc/tname.h
+++ b/src/common/inc/tname.h
@@ -54,7 +54,7 @@ typedef struct SSqlExpr {
   int32_t   resBytes;       // length of return value
   int32_t   interBytes;     // inter result buffer size
 
-  int16_t   colType;        // table column type
+  int16_t   colType;        // table column type, this should be int32_t, because it is too small for globale merge stage, pQueryAttr->interBytesForGlobal
   int16_t   colBytes;       // table column bytes
 
   int16_t   numOfParams;    // argument value of each function
diff --git a/src/query/inc/qAggMain.h b/src/query/inc/qAggMain.h
index 23e52bfaf97a9bf4923e54e5cdde87136a1c8ef9..aa5e2abd803d611be005115ba387a45e1138ed56 100644
--- a/src/query/inc/qAggMain.h
+++ b/src/query/inc/qAggMain.h
@@ -175,7 +175,7 @@ typedef struct SQLFunctionCtx {
   void *       pInput;    // input data buffer
   uint32_t     order;     // asc|desc
   int16_t      inputType;
-  int16_t      inputBytes;
+  int32_t      inputBytes;
   
   int16_t      outputType;
   int32_t      outputBytes;   // size of results, determined by function and input column data type
@@ -202,7 +202,7 @@ typedef struct SQLFunctionCtx {
   SPoint1      start;
   SPoint1      end;
 
-  SHashObj     *pUniqueSet;   // for unique function
+  SHashObj     **pUniqueSet;   // for unique function
 } SQLFunctionCtx;
 
 typedef struct SAggFunctionInfo {
diff --git a/src/query/inc/qExecutor.h b/src/query/inc/qExecutor.h
index ffe8e48aa011aeda1be3303093ea88ee0ef878e7..c4aebc07b15749da343b4d0175812ca6e4211021 100644
--- a/src/query/inc/qExecutor.h
+++ b/src/query/inc/qExecutor.h
@@ -90,6 +90,7 @@ typedef struct SResultRow {
   SResultRowCellInfo*  pCellInfo;  // For each result column, there is a resultInfo
   STimeWindow   win;
   char         *key;               // start key of current result row
+  SHashObj     *uniqueHash;  // for unique function
 } SResultRow;
 
 typedef struct SResultRowCell {
@@ -282,7 +283,7 @@ typedef struct SQueryAttr {
   STableGroupInfo  tableGroupInfo;       // table <tid, last_key> list  SArray<STableKeyInfo>
   int32_t          vgId;
   SArray          *pUdfInfo;             // no need to free
-  int32_t          maxUniqueResult;
+  int32_t          interBytesForGlobal;
 } SQueryAttr;
 
 typedef SSDataBlock* (*__operator_fn_t)(void* param, bool* newgroup);
diff --git a/src/query/inc/qUtil.h b/src/query/inc/qUtil.h
index 0882df77c2a8bc38560269ce093568fd96467dae..ce0a0648f554e007e46d441d9607d1d8edb971e3 100644
--- a/src/query/inc/qUtil.h
+++ b/src/query/inc/qUtil.h
@@ -70,8 +70,12 @@ static FORCE_INLINE char* getPosInResultPage(SQueryAttr* pQueryAttr, tFilePage*
                                              int32_t offset) {
   assert(rowOffset >= 0 && pQueryAttr != NULL);
 
-  int32_t numOfRows = (int32_t)getRowNumForMultioutput(pQueryAttr, pQueryAttr->topBotQuery, pQueryAttr->stableQuery);
-  return ((char *)page->data) + rowOffset + offset * numOfRows;
+  int64_t numOfRows = (int64_t)getRowNumForMultioutput(pQueryAttr, pQueryAttr->topBotQuery, pQueryAttr->stableQuery);
+  numOfRows *= offset;
+  if(numOfRows >= INT32_MAX){
+    assert(0);
+  }
+  return ((char *)page->data) + rowOffset + numOfRows;
 }
 
 bool isNullOperator(SColumnFilterElem *pFilter, const char* minval, const char* maxval, int16_t type);
diff --git a/src/query/src/qAggMain.c b/src/query/src/qAggMain.c
index b2a54f9c60b3910abcbb5b7726ede3a1b4eba78c..18ef2221b0db81ada8438524367baca81006e91f 100644
--- a/src/query/src/qAggMain.c
+++ b/src/query/src/qAggMain.c
@@ -5190,11 +5190,13 @@ static bool unique_function_setup(SQLFunctionCtx *pCtx, SResultRowCellInfo* pRes
   if (!function_setup(pCtx, pResInfo)) {
     return false;
   }
+  *pCtx->pUniqueSet = taosHashInit(64, taosGetDefaultHashFunction(TSDB_DATA_TYPE_BINARY), true, HASH_NO_LOCK);
+
   return true;
 }
 
 static void do_unique_function(SQLFunctionCtx *pCtx, SUniqueFuncInfo *pInfo, TSKEY timestamp, char *pData, char *tag, int32_t bytes){
-  UniqueUnit *unique = taosHashGet(pCtx->pUniqueSet, pData, bytes);
+  UniqueUnit *unique = taosHashGet(*pCtx->pUniqueSet, pData, bytes);
   if (unique == NULL) {
     size_t size = sizeof(UniqueUnit) + bytes + pCtx->tagInfo.tagsLen;
     char *tmp = pInfo->res + pInfo->num * size;
@@ -5220,7 +5222,7 @@ static void do_unique_function(SQLFunctionCtx *pCtx, SUniqueFuncInfo *pInfo, TSK
       }
     }
 
-    taosHashPut(pCtx->pUniqueSet, pData, bytes, &tmp, sizeof(UniqueUnit*));
+    taosHashPut(*pCtx->pUniqueSet, pData, bytes, &tmp, sizeof(UniqueUnit*));
     pInfo->num++;
   }else if(unique->timestamp > timestamp){
     unique->timestamp = timestamp;
diff --git a/src/query/src/qExecutor.c b/src/query/src/qExecutor.c
index c4cfdd1d4d80beb6f896bef69201840d995de9a5..8d2bb10295a9d30933cbc6360ae1acb913626c1b 100644
--- a/src/query/src/qExecutor.c
+++ b/src/query/src/qExecutor.c
@@ -281,7 +281,7 @@ static int compareRowData(const void *a, const void *b, const void *userData) {
   tFilePage *page1 = getResBufPage(pRuntimeEnv->pResultBuf, pRow1->pageId);
   tFilePage *page2 = getResBufPage(pRuntimeEnv->pResultBuf, pRow2->pageId);
 
-  int16_t offset = supporter->dataOffset;
+  int32_t offset = supporter->dataOffset;
   char *in1  = getPosInResultPage(pRuntimeEnv->pQueryAttr, page1, pRow1->offset, offset);
   char *in2  = getPosInResultPage(pRuntimeEnv->pQueryAttr, page2, pRow2->offset, offset);
 
@@ -1964,8 +1964,12 @@ static SQLFunctionCtx* createSQLFunctionCtx(SQueryRuntimeEnv* pRuntimeEnv, SExpr
       pCtx->requireNull = false;
     }
 
-    pCtx->inputBytes = pSqlExpr->colBytes;
     pCtx->inputType  = pSqlExpr->colType;
+    if (pRuntimeEnv->pQueryAttr->interBytesForGlobal > INT16_MAX && pSqlExpr->functionId == TSDB_FUNC_UNIQUE){
+      pCtx->inputBytes  = pRuntimeEnv->pQueryAttr->interBytesForGlobal;
+    }else{
+      pCtx->inputBytes = pSqlExpr->colBytes;
+    }
 
     pCtx->ptsOutputBuf = NULL;
 
@@ -2030,8 +2034,6 @@ static SQLFunctionCtx* createSQLFunctionCtx(SQueryRuntimeEnv* pRuntimeEnv, SExpr
       pCtx->param[2].nType = TSDB_DATA_TYPE_BIGINT;
     } else if (functionId == TSDB_FUNC_SCALAR_EXPR) {
       pCtx->param[1].pz = (char*) &pRuntimeEnv->sasArray[i];
-    } else if (functionId == TSDB_FUNC_UNIQUE){
-      pCtx->pUniqueSet = taosHashInit(64, taosGetDefaultHashFunction(TSDB_DATA_TYPE_BINARY), true, HASH_NO_LOCK);
     }
   }
 
@@ -2056,9 +2058,6 @@ static void* destroySQLFunctionCtx(SQLFunctionCtx* pCtx, int32_t numOfOutput) {
 
     tVariantDestroy(&pCtx[i].tag);
     tfree(pCtx[i].tagInfo.pTagCtxList);
-    if (pCtx[i].functionId == TSDB_FUNC_UNIQUE){
-      taosHashClear(pCtx[i].pUniqueSet);
-    }
   }
 
   tfree(pCtx);
@@ -3688,6 +3687,7 @@ void setDefaultOutputBuf(SQueryRuntimeEnv *pRuntimeEnv, SOptrBasicInfo *pInfo, i
     RESET_RESULT_INFO(pCellInfo);
 
     pCtx[i].resultInfo   = pCellInfo;
+    pCtx[i].pUniqueSet   = &pRow->uniqueHash;
     pCtx[i].pOutput      = pData->pData;
     pCtx[i].currentStage = stage;
     assert(pCtx[i].pOutput != NULL);
@@ -4022,6 +4022,7 @@ void setResultRowOutputBufInitCtx(SQueryRuntimeEnv *pRuntimeEnv, SResultRow *pRe
   int32_t offset = 0;
   for (int32_t i = 0; i < numOfOutput; ++i) {
     pCtx[i].resultInfo = getResultCell(pResult, i, rowCellInfoOffset);
+    pCtx[i].pUniqueSet = &pResult->uniqueHash;
 
     SResultRowCellInfo* pResInfo = pCtx[i].resultInfo;
     if (pResInfo->initialized && pResInfo->complete) {
@@ -4097,7 +4098,7 @@ void setResultOutputBuf(SQueryRuntimeEnv *pRuntimeEnv, SResultRow *pResult, SQLF
   // Note: pResult->pos[i]->num == 0, there is only fixed number of results for each group
   tFilePage *page = getResBufPage(pRuntimeEnv->pResultBuf, pResult->pageId);
 
-  int16_t offset = 0;
+  int32_t offset = 0;
   for (int32_t i = 0; i < numOfCols; ++i) {
     pCtx[i].pOutput = getPosInResultPage(pRuntimeEnv->pQueryAttr, page, pResult->offset, offset);
     offset += pCtx[i].outputBytes;
@@ -4115,6 +4116,7 @@ void setResultOutputBuf(SQueryRuntimeEnv *pRuntimeEnv, SResultRow *pResult, SQLF
      * not all queries require the interResultBuf, such as COUNT
      */
     pCtx[i].resultInfo = getResultCell(pResult, i, rowCellInfoOffset);
+    pCtx[i].pUniqueSet = &pResult->uniqueHash;
   }
 }
 
diff --git a/src/query/src/qUtil.c b/src/query/src/qUtil.c
index c585f44050c2db603952c1e53ceb21098571f772..1490564970692d258e150722b2407d74f8a4e628 100644
--- a/src/query/src/qUtil.c
+++ b/src/query/src/qUtil.c
@@ -88,6 +88,9 @@ void cleanupResultRowInfo(SResultRowInfo *pResultRowInfo) {
   for(int32_t i = 0; i < pResultRowInfo->size; ++i) {
     if (pResultRowInfo->pResult[i]) {
       tfree(pResultRowInfo->pResult[i]->key);
+      if (pResultRowInfo->pResult[i]->uniqueHash){
+        taosHashCleanup(pResultRowInfo->pResult[i]->uniqueHash);
+      }
     }
   }
   
@@ -153,11 +156,11 @@ void clearResultRow(SQueryRuntimeEnv *pRuntimeEnv, SResultRow *pResultRow, int16
   if (pResultRow->pageId >= 0) {
     tFilePage *page = getResBufPage(pRuntimeEnv->pResultBuf, pResultRow->pageId);
 
-    int16_t offset = 0;
+    int32_t offset = 0;
     for (int32_t i = 0; i < pRuntimeEnv->pQueryAttr->numOfOutput; ++i) {
       SResultRowCellInfo *pResultInfo = &pResultRow->pCellInfo[i];
 
-      int16_t size = pRuntimeEnv->pQueryAttr->pExpr1[i].base.resBytes;
+      int32_t size = pRuntimeEnv->pQueryAttr->pExpr1[i].base.resBytes;
       char * s = getPosInResultPage(pRuntimeEnv->pQueryAttr, page, pResultRow->offset, offset);
       memset(s, 0, size);