title: Filter Postgre query after percent_rank()
body: <p>I am trying to figure out how to correctly do this PostgreSQL query.
  I have a 'points' column, and I want to run a percent_rank on the points column, and then use a WHERE clause to filter out people below a certain rank AFTER the percent rank has already been calculated. It seems like by default the where clause takes place before the percent_rank, which is fine because I do want to filter out some things before the rank is calculated, but then filter it more after it is calculated.</p>
  <p>For example:</p>
  <pre><code>SELECT name,points,PERCENT_RANK() OVER (ORDER BY points) 
  FROM users 
  WHERE username IS NOT NULL 
  AND is_active = TRUE
  </code></pre>
  <p>and then filter this by only people with a percent_rank &gt; .10 or some other filter.</p>