How to avoid NULL check in JOIN condition in Tableau

Question

I'm attempting to alter the Tableau dashboard's backend database. Tableau generates JOIN SQLs that include conditions like: ON a.col1 = b.col2 OR (a.col1 is null and b.col2 is null) Is there a method to avoid the OR condition (a.col1 is null and b.col2 is null)? I tried using ZN and IFNULL with the column name, but the conditions continue to be added. The Druid DB only supports JOIN with equality conditions, and the query fails due to the IS NULL check. Thanks