完整报错信息如下：
There is no data for the selected MySQL instance, time range or search query.
QAN API error: “qh.Profile: No query classes for selected instance and time range. Please check whether your MySQL settings match the recommended.”.
Check the /var/log/qan-api.log file in docker container for more information.
解决方法：
PMM使用slow log作为查询源，需要开启慢日志：
slow_query_log=ON
long_query_time=0
