title: #1305 FUNCTION dbname.json_arrayagg does not exist
body: <p>maybe I miss something. But why do this function doesn't exist?</p>
  
  <p>Based on the documentation it should be:
  <a href="https://dev.mysql.com/doc/refman/5.7/en/group-by-functions.html" rel="nofollow noreferrer">https://dev.mysql.com/doc/refman/5.7/en/group-by-functions.html</a></p>
  
  <p>Version: 5.7.21-0ubuntu0.16.04.1</p>
  
  <p>Somebody help me out pls :) This function could help me out well.</p>