title: spark 1.5.2 left outer join not working
body: <p>I have  two dataframes</p>
  
  <ul>
  <li>df1 with 500 columns, one of which is id(StringType) and number of records 10 million</li>
  <li>df2 with 4 columns, one of which is id(StringType) and other 3 columns(say x, y, z) name match with 3 columns of df1(same name, i.e. x, y, z), it contain 0.2 million records</li>
  </ul>
  
  <p>I want to do left join, hence join df must have 10 millions records with 500 columns </p>
  
  <pre><code>  df1.join(df2, "id", "left_outer")
  </code></pre>
  
  <p>it is giving me error
  error: type mismatch:</p>
  
  <pre><code>  found   : String("id")
    required: org.apache.spark.sql.Column
  </code></pre>
  
  <p>what to do, and when i'm trying </p>
  
  <p>it is giving me org.apache.spark.sql.AnalysisException: join condition 'id' of type string is not a boolean.</p>
  
  <p>what to do?</p>