title: spark dataframe filter conditions can't use string
body: <p>I used spark 1.3.0</p>
  
  <pre><code>df.filter("di4='test'").show()
  </code></pre>
  
  <p>and di4 is my column
  the error is </p>
  
  <pre><code>org.apache.hive.service.cli.HiveSQLException: AnalysisException: couldn't resolve column reference: 'test'
  </code></pre>
  
  <p>but when i try the </p>
  
  <pre><code>df.filter("di5=10").show()
  </code></pre>
  
  <p>its success
  anyone can help me? thanks</p>