title: How to query JSON data column using Spark DataFrames?
body: <p>I have a Cassandra table that for simplicity looks something like:</p>
  
  <pre><code>key: text
  jsonData: text
  blobData: blob
  </code></pre>
  
  <p>I can create a basic data frame for this using spark and the spark-cassandra-connector using:</p>
  
  <pre><code>val df = sqlContext.read
    .format("org.apache.spark.sql.cassandra")
    .options(Map("table" -&gt; "mytable", "keyspace" -&gt; "ks1"))
    .load()
  </code></pre>
  
  <p>I'm struggling though to expand the JSON data into its underlying structure.  I ultimately want to be able to filter based on the attributes within the json string and return the blob data.  Something like jsonData.foo = "bar" and return blobData.  Is this currently possible?</p>