Is Union Queries run in Parallel form or not.

[Azeem Haider]

I have three tables and I want to select data from these three tables in parallel form to increase the performance.

I'm running query like this.

SELECT * FROM table1
UNION ALL
SELECT * FROM table2
UNION ALL
SELECT * FROM table3

I wan to ask that these queries run in parallel form or in order one by one ?

What can I do to increase the performance of this query. Can I create thread for each query ?

If I create three thread for this query with single connection is it work in parallel or not ? or I need to create three connection for each query to run parallel ?