When we think about the performance of a database, indexing is the first thing that comes to the mind. Here, we are going to look into how database indexing works on a database. Please note that here, architectural details are described referenced to SQLite 2.x database architecture. You can find out the backend implementation of SQLite 2.5.0 with tests, which is relevant to this post from https://github.com/madushadhanushka/simple-sqlite.
Read how overall SQLite database architecture composed in this DZone article.