Upgrading to synchronous replication

So far, asynchronous replication has been covered in reasonable detail. However, asynchronous replication means that a commit on a replica is allowed to happen after the commit on a primary. If the primary crashes, data that hasn’t made it to the replica might be lost, even if replication is occurring.

Synchronous replication is here to solve the problem – if PostgreSQL replicates synchronously, a commit has to be flushed to disk by at least one replica to go through on the primary. Therefore, synchronous replication reduces the odds of data loss substantially.

In PostgreSQL, configuring synchronous replication is easy. Only two things have to be done (in any order):

• Adjust the synchronous_standby_names setting in the postgresql.conf file on the primary
• Add an application_name setting to the primary_conninfo parameter in the config file in the replica

Let’s get started with the postgresql.conf file on...