title: Count number of objects in JSON array stored as Hive string column
body: <p>I have a Hive table with a JSON string stored as a string in a column.
  Something like this.</p>
  
  <pre><code>Id                     |           Column1 (String)
  1                      | [{k1:v1,k2:v2},{k3:v3,k4:v4}]
  2                      | [{k1:v1,k2:v2}]
  </code></pre>
  
  <p>I want to count the number of JSON objects in the column.</p>
  
  <pre><code>Id                     |           Count
  1                      |             2
  2                      |             1  
  </code></pre>
  
  <p>What would be the query to achieve this?</p>