title: Listagg Alternative in Spark SQL
body: <p>I want to aggregate ASINs , grouping it by customerID like this:</p>
  
  <pre><code>Input:
  C1 - O1
  
  C1 - o2
  
  C2 - o3
  
  C2 - o4
  
  Output:
  
  C1 - o1, o2
  
  C2 - o3, o4
  </code></pre>
  
  <p>In Redshift, I used to this using LISTAGG function. However, it doesn't seem to be working inSpark SQL. is there an alternative for this in SparkSQL?</p>