Sql – How to write a simple database engine


I am interested in learning how a database engine works (i.e. the internals of it). I know most of the basic data structures taught in CS (trees, hash tables, lists, etc.) as well as a pretty good understanding of compiler theory (and have implemented a very simple interpreter) but I don't understand how to go about writing a database engine. I have searched for tutorials on the subject and I couldn't find any, so I am hoping someone else can point me in the right direction. Basically, I would like information on the following:

  • How the data is stored internally (i.e. how tables are represented, etc.)
  • How the engine finds data that it needs (e.g. run a SELECT query)
  • How data is inserted in a way that is fast and efficient

And any other topics that may be relevant to this. It doesn't have to be an on-disk database – even an in-memory database is fine (if it is easier) because I just want to learn the principals behind it.

Many thanks for your help.

Best Answer

If you're good at reading code, studying SQLite will teach you a whole boatload about database design. It's small, so it's easier to wrap your head around. But it's also professionally written.