proxysql series - principles and operation and maintenance analysis

Detecting a master-slave mechanism
   by admin detect the return value
        select hostgroup_id, hostname, port, status , max_replication_lag from runtime_mysql_servers;
   detecting statements
        show slave status
  detection frequency
        mysql-monitor_replication_lag_interval: primary delay from the detection time, 10 seconds by default.
  Detected value
       second_master_behind max_replication_lag non-NULL
       second_master_behind is NULL (copy abnormal situation)
       MySQL-60s in terms of default monitor_slave_lag_when_null max_replication_lag = 60 (this parameter is a problem to be authenticated)
two multiplexed connection pool
     where: DB is connected to a rear end, can " at the same time "used by multiple clients 
     improved contrast
     conventional connection pool, disconnects (session) after the client, he returned to the connection pool.
     In ProxySQL, because the connection multiplexing, the connection after the end of the sql statement is executed, it puts back in connection pool (client sessions might not disconnect), which can greatly improve the efficiency of the back-end connections, and avoid too large rear preceding request connections soaring.