Up to now, this chapter has hopefully provided some insight into how PostgreSQL writes data and what the XLOG is used for in general. Given this knowledge, we can now move on and learn what we can do to make our databases work even more efficiently, both, in case of replication and in case of running just a single server.
In this chapter, we have seen that data has to be written to the XLOG before it may go anywhere. The thing is, if the XLOG was never deleted, clearly, we would not write to it forever without filling up the disk at some point in time.
To solve the problem, the XLOG has to be deleted at some point. This process is called checkpointing.
The main question arising from this ...