diff --git a/src/client/src/tscFunctionImpl.c b/src/client/src/tscFunctionImpl.c
index f5a27311f2333ba172bf5d2e484aede49b17c5ab..35dc94f37bccf46ba95cee119faef3921a63705e 100644
--- a/src/client/src/tscFunctionImpl.c
+++ b/src/client/src/tscFunctionImpl.c
@@ -2695,17 +2695,18 @@ static void apercentile_func_second_merge(SQLFunctionCtx *pCtx) {
   }
   
   SAPercentileInfo *pOutput = getAPerctInfo(pCtx);
-  SHistogramInfo *  pHisto = pOutput->pHisto;
+  SHistogramInfo  *pHisto = pOutput->pHisto;
   
   if (pHisto->numOfElems <= 0) {
     memcpy(pHisto, pInput->pHisto, sizeof(SHistogramInfo) + sizeof(SHistBin) * (MAX_HISTOGRAM_BIN + 1));
     pHisto->elems = (SHistBin*) ((char *)pHisto + sizeof(SHistogramInfo));
   } else {
+    //TODO(dengyihao): avoid memcpy   
     pHisto->elems = (SHistBin*) ((char *)pHisto + sizeof(SHistogramInfo));
-    
     SHistogramInfo *pRes = tHistogramMerge(pHisto, pInput->pHisto, MAX_HISTOGRAM_BIN);
-    tHistogramDestroy(&pOutput->pHisto);
-    pOutput->pHisto = pRes;
+    memcpy(pHisto, pRes, sizeof(SHistogramInfo) + sizeof(SHistBin) * MAX_HISTOGRAM_BIN);
+    pHisto->elems = (SHistBin*) ((char *)pHisto + sizeof(SHistogramInfo));
+    tHistogramDestroy(&pRes);
   }
   
   SResultRowCellInfo *pResInfo = GET_RES_INFO(pCtx);
diff --git a/src/query/inc/qHistogram.h b/src/query/inc/qHistogram.h
index 4f5c7386492d410cd6711dc6c63c565d60237743..442e61750b06d269ef48c5e74ede7646f7ac62e1 100644
--- a/src/query/inc/qHistogram.h
+++ b/src/query/inc/qHistogram.h
@@ -45,7 +45,6 @@ typedef struct SHistogramInfo {
   int32_t maxEntries;
   double min;
   double max;
-
 #if defined(USE_ARRAYLIST)
   SHistBin* elems;
 #else