In my current project, the DB is SQL 2005 and the load is around 35 transactions/second. The client is expecting more business and are planning for 300 transactions/second. Currently even with good infrastructure, DB is having performance issues. A typical transaction will have at least one update/insert and a couple of selects.
Have you guys worked on any systems that handled more than 300 txn/s running on SQL 2005 or 2008, if so what kind of infrastructure did you use how complex were the transactions? Please share your experience. Someone has already suggested using Teradata and I want to know if this is really needed or not. Not my job exactly, but curious about how much SQL can handle.
According to tcp.org its possible for SQL Server 2005 to get 1,379 transactions per second. Here is a link to a system that's done it. (There are SQL Server based systems on that site that have far more transactions... the one I linked was just the first I one I looked at).
Of course, as Kragen mentioned, whether you can achieve these results is impossible for anyone here to say.