Programmers love to talk about performance but only a few talk about scalability, despite of the fact that it is only scalability that counts. Scalability is about how your effort has to grow with your success. This is what you must have in mind if you start a business for the web.
It is always a good idea to plan a new project for scalability from the first steps on. There are some easy task with just a little overhead in development but great benefit if your project reaches the level of success you've intended.
- divide and conquer in size and time
- use a good abstraction layer for data access to be free if you need to partition data
- avoid complicated joins and excessive normalization, they'll kill you if you have to distribute data over multiple data bases and mashines
- do you really need relational database schemas for everything or may a simple key-value-storage work as well
- cache data access from the beginning
- cache more, compute less
- use functional decomposition, partition your system in tiny and efficient units and plug them together by abstraction
- use asynchronous strategies to manage load peaks
- split static and dynamic content carefully, soon you may need a CDN to deliver static content
- apply a good deployment strategy with rollback
- measure and monitor performance and scalability systematically
- scale your revenue in parallel with your technology
Don't miss the last point. It's the most important.
