title: Grafana / Influxdb: Sum of value recorded by different clients
body: <p>I'm recording series such as <em>memory_used</em> with a couple of clients using the influxdb-java client into an InfluxDB database. The data look like this:</p>
  
  <pre><code>1449433668 19292838 client=clientA
  1449433999 24448880 client=clientB
  </code></pre>
  
  <p>I can easily graph the memory usage grouped by tag using grafana, however I couldn't find a way to sum up the total memory consumption by all clients. When using avg(memory_used) or sum(memory_used) the values are way to large and fluctuate. I think this is because values for the same client may be summed up multiple times depending on the reported interval (which is not exactly the same).</p>
  
  <p>How can I sum up the total memory consumption in this case? Should I code my clients to eg. always report values every 5 seconds and truncate the milliseconds?</p>