Ruby on Rails

I'm developing a polling application that will deal with an average of 1000-2000 votes per second coming from different users. In other words, it'll receive 1k to 2k requests per second with each request making a DB insert into the table that stores the voting data.

I'm using RoR 4 with MySQL and planning to push it to Heroku or AWS.

What performance issues related to database and the application itself should I be aware of?

How can I address this amount of inserts per second into the database?

EDIT

I was thinking in not inserting into the DB for each request, but instead writing to a memory stream the insert data. So I would have a scheduled job running every second that would read from this memory stream and generate a bulk insert, avoiding each insert to be made atomically. But i cannot think in a nice way to implement this.