====== Grafana ======

==== Kilobytes per second ====
From my [[Projects/load logger]] project I collect the number of bytes in/out of my network devices.  If I want to graph that in grafana using my MySQL data source (as KB/s) then I have to use SQL to munge the numbers.  This gets what I need in SQL:
<code sql>
select
      id,
      created_on,
      n4_r, 
      ((n4_r - @lastValue) / 1024 ) as AvgKbPerSec,
      @lastValue := n4_r
   from
      data_logger,
      ( select @lastValue := 0 ) SQLVars
   order by
created_on,id
</code>

Then to get it working with Grafana, I change it to this (wrapped in an extra select, because graphana only wants one value to graph):
<code sql>
select time, KbPerSec from (
select
      created_on as "time",
      if(@lastValue = 0, 0, ((n4_r - @lastValue) / 1024 )) as Kb,
      @lastValue := n4_r
   from
      data_logger,
      ( select @lastValue := 0 ) SQLVars
 where $__timeFilter(created_on)
   order by
created_on) as newtable 
 where $__timeFilter(time)
   order by
time
</code>