title: How to get the current free disk space in Postgres?
body: <p>I need to be sure that I have at least 1Gb of free disk space before start doing some work in my database. I'm looking for something like this:</p>
  
  <pre><code>select pg_get_free_disk_space();
  </code></pre>
  
  <p>Is it possible? (I found nothing about it in docs).</p>
  
  <p>PG: 9.3  &amp; OS: Linux/Windows</p>