In this series, we have looked at the "musts" (databases) and "shoulds" (asynchronous jobs, websockets) of a web application. Now we turn to one of the "coulds" (that is nonetheless recommended for scaling businesses): caching. In particular, we mean caching HTML fragments and other snippets of data, as referred to in Rails Guides. We are not concerned with HTTP or SQL query caching. In this part, we'll see how to speed up our Rails app using LiteCache.
Primary keys are vital in the design of a relational database. They are crucial in uniquely identifying records. For example, if you have a table of users, you will need to identify each record uniquely. This is where primary keys are used. Primary keys are usually single columns that auto-increment. There might be cases where you'll need a combination of column to serve as the primary key - this is where composite primary keys become helpful.