In this chapter, you learned about the purpose of the PostgreSQL transaction log. We talked extensively about the on-disk data format and some highly important topics, such as consistency and performance. All of them will be needed when we replicate our first database in the next chapter.
The next chapter will build on top of what you have just learned, and focus on Point-in-time-Recovery (PITR). Therefore, the goal will be to make PostgreSQL return to a certain point in time and provide data as if some later transactions never happened.