The synchronous_commit configuration parameter has another, more relevant setting for those interested in high availability. The default functionality of a synchronous standby is to consume transactions from the replication stream and acknowledge receipt. Yet this only means the data has been physically written to disk on the replica system. There's still the very slim chance that a crash of the synchronous standby might prevent transactions from reaching the actual data files on that system.
If we set synchronous_commit to remote_apply however, the result is subtly different. This value is only available in PostgreSQL 9.6 and higher and it makes synchronous replication even more strict in its implementation. With this value ...
