If I am going to have a data table with million records and every record is going to be update every 30 seconds. Where should I save all this table data?

I have a problem in data base. I am using MySQL to save important data as needed, but I also have to save data that is not important to save, just need to use it for my purpose.

Where should I save this data?

I think saving it in DB is a bad idea, because of the dynamic update of records every few seconds. I am thinking about 1 million users who update this table every few seconds. It probably going to kill my DB.

What do you think?