What do you think , what DB paypal uses ? Sybase ? MySQL ? MS SQL ? Oracle ? Something else ? Paypal process more than 1000000 records every seconds...I guess
Probably Oracle, DB2 or MSSQL. I really doubt that they are using MySQL. If that number is correct, I would have to say Oracle. There's nothing else I can think of that could be trusted for such a volume.
Oracle is the most plausible thing. As thewebhostingdir said they might be using MySQL enterprise. There's only 1 thing for sure. They don't use mysql .
Based on when they got started and their business model, MySQL really doesn't fit their profile. Google uses, and makes MySQL better, but Paypal has no interest in figuring out how to make something work. When you're in the financial services sector, with 1M database transactions per second, you use what works, and the only database that can scale to that level reliably is Oracle. Anyway, just my opinion, but I'm in financial services, and if I were in their position, Oracle would be the only choice.