In this chapter, we have outlined the basic concept of synchronous replication, and we have shown how data can be replicated synchronously. We have also shown how durability requirements can be changed on the fly by modifying PostgreSQL runtime parameters. PostgreSQL gives users the choice of how a transaction should be replicated, and which level of durability is necessary for a certain transaction.

In the next chapter, we will dive into monitoring and see how you can figure out if your replicated setup is working as expected. We will present some tricks making it easy to see if your cluster is performing as expected.