How many times have you got an answer that applies to your specific scenario when providing a short list of performance and scalability requirements? MySQL/InnoDB can do 750k qps, Cassandra is scaling linearly, MongoDB can do 8 mil ops/s. Is any of these the answer for your application?
How many times did you get all the requirements right at the spec time?
How many times did requirements remain the same during the development cycle?
How many times did production reality confirmed your bullet list requirements?
Original title and link: Asking for Performance and Scalability Advice on StackOverflow ( ©myNoSQL)