[td-1764] fix memory leak.

src/client/src/tscLocalMerge.c

@@ -510,7 +510,8 @@ void tscDestroyLocalReducer(SSqlObj *pSql) {
     taosTFree(pLocalReducer->pResultBuf);
 
     if (pLocalReducer->pResInfo != NULL) {
-      for (int32_t i = 0; i < pQueryInfo->fieldsInfo.numOfOutput; ++i) {
+      size_t num = tscSqlExprNumOfExprs(pQueryInfo);
+      for (int32_t i = 0; i < num; ++i) {
         taosTFree(pLocalReducer->pResInfo[i].interResultBuf);
       }
 

src/client/src/tscUtil.c

@@ -972,6 +972,8 @@ void tscFieldInfoClear(SFieldInfo* pFieldInfo) {
   }
   
   taosArrayDestroy(pFieldInfo->internalField);
+  taosTFree(pFieldInfo->final);
+
   memset(pFieldInfo, 0, sizeof(SFieldInfo));
 }
 
@@ -1834,7 +1836,7 @@ static void doSetSqlExprAndResultFieldInfo(SQueryInfo* pQueryInfo, SQueryInfo* p
     return;
   }
 
-  // set the field info in pNewQueryInfo object
+  // set the field info in pNewQueryInfo object according to sqlExpr information
   size_t numOfExprs = tscSqlExprNumOfExprs(pNewQueryInfo);
   for (int32_t i = 0; i < numOfExprs; ++i) {
     SSqlExpr* pExpr = tscSqlExprGet(pNewQueryInfo, i);