title: Filtering Data in Apache Pig
body: <p>Hey I am trying to filter the following Input:</p>
  
  <pre><code>Id       Num
  102369   100
  623589   200
  102369   300
  103333   300
  103333   100
  ...
  </code></pre>
  
  <p>Expected output relation should be reduced and only include all <code>ID</code> - <code>Num</code> relations for existing relations between <code>Id</code> and <code>Num == 300</code>:</p>
  
  <pre><code>Id     Num
  102369 100
  102369 300
  103333 300
  103333 100
  </code></pre>
  
  <p>I have tried it like this:</p>
  
  <pre><code>grouped = GROUP table BY Num;
  filtered = FILTER grouped BY group == 300;
  DUMP filtered;
  </code></pre>
  
  <p>But this does not work. Can you help me to solve this?</p>
  
  <p>Kind regards.</p>