title: MySQL default queries
body: <p>Since yesterday I have been using navicat monitor to see what frequently used querys are in my database.
  Now it appears that with the slow query log it is mainly querys that are done by the database itself. The two that have already been executed 55000 times within 12 hours are as follows:</p>
  
  <pre><code>SELECT SUBSTRING_INDEX(event_name, '/', -1) AS wait_type
       , sum_timer_wait / 1000000000000 AS wait_time 
    FROM performance_schema.events_stages_summary_global_by_event_name 
   WHERE ( sum_timer_wait / 1000000000000 ) &gt; 0.01
  
  SELECT a.digest 
       , a.thread_id session_id
       , USER db_user
       , SUBSTRING_INDEX( HOST, ':', 1 ) machine
       , db db_name
       , ATTR_VALUE program
       , sum( timer_wait ) timer_wait 
    FROM performance_schema.events_statements_history a 
    LEFT 
    JOIN performance_schema.threads b 
      ON a.THREAD_ID = b.THREAD_ID 
    LEFT 
    JOIN INFORMATION_SCHEMA.PROCESSLIST c 
      ON b.PROCESSLIST_ID = c.ID 
    LEFT   
    JOIN performance_schema.session_connect_attrs d
      ON c.id = d.PROCESSLIST_ID 
   WHERE timer_wait/1000000000 &gt; 0.5 
     and a.sql_text IS NOT NULL 
     AND ( d.ATTR_NAME = "_client_name" OR d.ATTR_NAME IS NULL ) 
   GROUP 
      BY a.thread_id
       , a.digest
       , db_user
       , machine
       , program
       , db_name 
  </code></pre>
  
  <p>Now my question is what do these do? And are these not superfluous, as if they cannot stop? And if so how?</p>