title: Postgresql 9.6 parallel execution don't work
body: <p>I installed a Postgresql 9.6 on an Ubuntu 16.04 Server and did the same steps as in this blog:</p>
  
  <p><a href="http://blog.2ndquadrant.com/postgresql96-parallel-sequential-scan/" rel="nofollow">http://blog.2ndquadrant.com/postgresql96-parallel-sequential-scan/</a></p>
  
  <ol>
  <li>set max_parallel_workers_per_gather to 8 </li>
  <li><code>CREATE TABLE test (i int);</code></li>
  <li><code>INSERT INTO test SELECT generate_series(1,100000000);</code></li>
  <li><code>ANALYSE test;</code></li>
  </ol>
  
  <p>But there is no parallelization, neither in the execution plan nor visible with htop.</p>
  
  <p>Is there something else to care of to activate parallelization?</p>
  
  <p><strong>Edit</strong>
  Queries I tried:</p>
  
  <ol>
  <li><code>SELECT * FROM test;</code> </li>
  <li><code>SELECT * FROM test WHERE i=1;</code> </li>
  <li><code>SELECT * FROM test WHERE i&lt;90000000;</code></li>
  <li><code>SELECT count(*) from test;</code> </li>
  </ol>