Database for efficient retrieval of data from large data set I am designing a new system that will be dealing with large data set. This system is expected to have over 10 million records. A user of the system needs to check for the availability of the name he wants to register. If nothing is returned, that means the name is available, the user can then proceed to register the name.

The database needs to be optimized for search. I was considering using mysql, but i don't know if there are better options. Thanks
All you need here is to make the username a unique index and MySQL will (generally) handle this very well. 

Unfortunately, I had to write 'generally' because there can be many many other factors on your system that could slow this down. I recommend having MySQL 5.5 and the table be InnoDB. Proper indexing and configuration will go a long way in helping you.

The short of it is, MySQL/InnoDB is easily able to handle 10 million rows.