title: redshift array_to_string does not work with union
body: <p>I am attempting to run array_to_string with a union in redshift but i keep getting the following error message:</p>
  
  <pre><code>ERROR: Specified types or functions (one per INFO message) not supported on Redshift tables. [SQL State=0A000] 
  </code></pre>
  
  <p>The query itself is pretty straight forward, so i am not sure why i keep getting this, can someone please advise</p>
  
  <pre><code>(SELECT array_to_string(array(select column_name::text from information_schema.columns where table_name= 'customer_insert' order by ordinal_position),'|'))
  UNION 
  (select "user.firstname"::text from digital.customer_insert where "user.isocountrycode" = 'BE' limit 2)
  </code></pre>