You may not be able to get Custom SQL in BigQuery to suit your needs until we release v8.1. If you are a member of our Beta program, consider testing your desired behavior in the 8.1 beta and give us feedback.
This is good news for 8.1! Do you know if there are going to be any other new features supported for BigQuery in 8.1?
So after spending half the day, trying to Union 2 tables i finally realized that Tableau 8.0 does not support custom SQL for union of 2 or more tables using BigQuery as the database. (even if the datatype and schema are matching)
But did anyone find a workaround this for 8.0?
In 8.1 it works fine.