What's this chapter about?

It is defacto standard that SQLite database is default databases for almost every mobile platforms including Android and iOS (although there are some move to change default database).

SQLite provides two journal modes RBJ (Rollback Journal) and WAL(Write Ahead Log). SQLite summary describes two journal modes.

Simple Optimization of SQLite with BtrFS

This optimization technique that I implemented decreases write amplification by SQLite on BtrFS filesystems.

BtrFS's Opportunity describes the details of opportunity in BtrFS and the optimization technique.

SQLite WAL mode has already changed.
SQLite RBJ mode is still in progress.
You can find the source codes from Github: SQLite.