Issue

The order in which the SQL query is issued for each table is not the same as the order of the flow process in Tableau Prep. 
For example, when running the sample flow in the below image, the SQL should be [cal1 / cal --> demo1], however, the actual SQL order in the log is [demo1 --> cal --> cal1] to database.
What is the rule for the order of SQL from Tableau Prep?