Ongoing DSP Adserver Porject. Require an expert to improve scalability

Hi, I am looking for a Developer who is expert in scaling a system that can handle like a billion Ad impressions/clicks per day . This job requires someone who has a good understanding on how clustering work , which database engine to select for such task and how to transfer huge data between server for reporting . This is an ongoing project with alredy over 7 highly skilled programmers. Its a long term project. Please only bid if you already have experience with such projects.