title: Big data amounts with Highcharts / Highstock (async loading)
body: <p>Since my data amount becomes bigger everyday (right now > 200k MySQL rows in one week), the chart is very slow at loading. I guess the async loading method is the right way to go here (<a href="http://www.highcharts.com/stock/demo/lazy-loading" rel="nofollow noreferrer">http://www.highcharts.com/stock/demo/lazy-loading</a>).
  I tried to implement it, but it doesn't work. So far I can provide my data with Python via URL parameters e.g. <a href="http://www.url.de/data?start=1482848100&amp;end=1483107000" rel="nofollow noreferrer">http://www.url.de/data?start=1482848100&amp;end=1483107000</a>, but there are several things I don't understand in the example code:</p>
  
  <ul>
  <li>If a period of All Data is chosen in the Navigator, then all data is
  provided by my server and loaded by the chart. So its the same as I
  what I do right now without lazy loading. Whats the difference then?</li>
  <li>Why there is a second getJSON() method without any URL parameter in
  the above mentioned example code? Its the following URL, which is empty. What do I
  need it for? I don't understand it:
  <a href="https://www.highcharts.com/samples/data/from-sql.php?callback=" rel="nofollow noreferrer">https://www.highcharts.com/samples/data/from-sql.php?callback=</a>?</li>
  </ul>
  
  <p>And which method to load the data is better?: 
  This one: <code>chart.series[0].setData(data);</code>
  or the code below which I use so far:</p>
  
  <pre><code>var ohlc = [],
  volume = [],
  dataLength = data.length,
  i = 0;
  for (i; i &lt; dataLength; i += 1) {
  ohlc.push([
  data[i]['0'], // date
  data[i]['1_x'], // open
  data[i]['2_x'], // high
  data[i]['3'], // low
  data[i]['4'] // close  ]);
  </code></pre>