I have a tableau dashboard connected to a view. The data to this view is coming from 2 identical tables that gets refreshed with same data but during different time instance.
I need the data in the view to be latest all the time. Both tables have a date column where all the values are same that is the time it got refreshed.

Eg when table1 get refreshed with latest data the view should take data from table1
When table1 and table2 has same data take data from table1
When table2 has latest data take data from table2.

Both the tables are from a data warehouse with huge volume of data. So doing an union and filtering by date is not cost effective. Is there a way to do a if else condition to perform while selecting between 2 tables.

I tried doing union and filtering by latest date. Even it worked it has affected the performance.