Reviewing LevelDB, Part I: What is This All About

leveldb is…

a fast key-value storage library written at google that provides an ordered mapping from string keys to string values.

that is the project’s own definition. basically, it is a way for users to store data in an efficient manner. it isn’t a sql database . it isn’t even a real database in any sense of the word. what it is is a building block for building databases. it handles writing and reading to disk, and it supports atomicity. but anything else is on you (from transaction management to more complex items).

as such, it appears perfect for the kind of things that we need to do. i decided that i wanted to get to know the codebase, especially since at this time, i can’t even get it to compile . the fact that this is a c++ codebase, written by people who eat & breath c++ for a living is another reason why. i expect that this would be a good codebase, so i might as well sharpen my c++-foo at the same time that i grok what this is doing.

the first thing to do is to look at the interface that the database provides us with:

that is a very small surface area, and as you can imagine, this is something that i highly approve of. it make it much easier to understand and reason about. and there is some pretty complex behavior behind this, which i’ll be exploring soon.