title: lubcurl put data to the end of a string
body: <p>i will write cycling data to my cloud to display the values in a trend on a html page.</p>
  
  <pre><code>$ curl -X PUT  -d '{"x": 10, "y": 20}' https://...firebaseio.com/trend.json
  </code></pre>
  
  <p>My question is what is the best way to do this.
  My idea is it to write a string and add the new value behind them.
  Or is it better to create a ring buffer with a fix size like this?</p>
  
  <pre><code>$ curl -X PUT  -d '{"x.1": 10, "y.1": 20}' https://...firebaseio.com/trend.json
  </code></pre>
  
  <p>What is the best way?</p>
  
  <p>thanks for help and ideas</p>