Trying to speed up convert mongo into dataframe

cdplib/db_handlers/MongodbHandler.py

@@ -322,7 +322,7 @@ class MongodbHandler:
                 records = []
         if records:
             frames.append(pd.DataFrame(records))
-        return_df = pd.concat(frames)
+        return_df = pd.concat(frames, axis=0, sort=False)
         self._log.info(('{} Rows were fetched from {}. DataFrame conversion is done, took {} seconds').format(len(return_df.index), collection_name if collection_name is not None else 'the database', time.time()-start_time))
         
         return return_df