Re: Sending data in processlist

[Rick James]

Subqueries often are slow.
You have:

select  shutDownFlag, time_of_ping, observedstate, simulatedstate
    from  test100
    where  time_of_ping = 
      ( SELECT  max(time_of_ping)
            from  test100
            where  !(observedstate=4
                      and  powercost=0)
      )

See if this gives you what you want, but much faster:

SELECT  b.shutDownFlag, b.time_of_ping, b.observedstate, b.simulatedstate
    FROM  
      ( SELECT  max(time_of_ping) AS last_ping
            from  test100
            where  !(observedstate=4
                      and  powercost=0) 
      ) AS a
    JOIN  test100 AS b ON b.time_of_ping = a.last_ping;

Also, be sure to have time_of_ping indexed.