Hotswap mysql table

To alter a mysql table with minimal downtime. I have used this to alter table with size more than even 400GB.

Assumptions :

- id is the auto_increment column of the table 
- indexes present in both id and autoUpdateCol separately
- exception handling can be better; As DDL cannot be reverted/rollbacked
- works for addition of column, changing the columns meta, adding/removing indices
- fails in case of dropping a column ( insert into temp table will fail )