SQLAlchemy 1.1.4's New "server_side_cursors" Option
Before SQLAlchemy 1.1.4, if you wanted to stream your MySQL query using server side cursors, you would need to run your query using execution_options(stream_results=True) and pass SSCursor into create_engine’s connect_args. Now, all you need to do is pass server_side_cursors=True into create_engine and it will automatically stream the results for your select queries.
http://docs.sqlalchemy.org/en/latest/dialects/mysql.html#server-side-cursors