How to achieve Synonym switch(switching reference of one table to another table).

My requirement is An import data from a workflow to update real-time data to the campaign tables, scheduled for  Daily execution. The data expectation would be more than a million records. for this a down time of 30 min is expecting as per the test. so i need a solution to reduce that down time to ZERO min.

As a part of identifying solutions, I come across the switching tables.

To be specific:

offline data and online data.

In offline, data will be loaded to one table  say "customer".{another table which is already online with the same fields of "customer" table say "customer_backup"}

so i need to switch from customer_backup table to cusotmer table to be online so that the delay is skipped as the table is already loaded just need to switch.

Suggest me the activities, sql code activity usage, and any workflow to achieve this.

Thanks in Advance!