title: Vertica different calculations than in PostgreSQL
body: <p>I have one query:</p>
  
  <pre><code>SELECT CAST(((stats.ts_spawn - 1427835600) / 86400) * 86400 + 
  1427835600 AS INTEGER) AS anon_1 FROM stats WHERE stats.ts_spawn &gt; 
  1427835600 AND stats.ts_spawn &lt; 1428440399 GROUP BY anon_1 order by anon_1;
  </code></pre>
  
  <p>I'm expecting to get start of the each day in a week.</p>
  
  <p>Result in Postgresql:</p>
  
  <pre><code>1427835600
  1427922000
  1428008400
  1428094800
  1428181200
  1428267600
  1428354000
  </code></pre>
  
  <p>Vertica returns start of each hour of each day of the week:</p>
  
  <pre><code>1427839200
  1427842800
  1427846400
  1427850000
  ... and so on, total 167 records(24 * 7 - 1)
  </code></pre>
  
  <p>I have no idea how to modify this query.</p>