title: How to get max length of string column from dataframe using scala?
body: <p>This can be a really simple question. I am using Spark 1.6 with scala </p>
  
  <pre><code>var DF=hivecontext.sql("select name from myTable")
  val name_max_len =DF.agg(max(length($"name"))) // did not work
  
  println(name_max_len)
  </code></pre>
  
  <p>How can I get max length?</p>