One element that is absolutely required for any highly available PostgreSQL installation is replication. It does not matter whether we have a Storage Area Network (SAN) that provides disk redundancy, nor is Distributed Replicated Block Device (DRBD) or other block-level replication sufficient to protect our investment. Duplicating and backing up data is always a good practice, but when it comes to availability, we need online copies of the database.
Similarly, if other departments need data that resides in our Online Transactional Processing (OLTP) database, how can we provide it safely? In ideal circumstances, we can supply a copy of the necessary tables. This way, we don't strain the primary database with ad hoc report-based queries. A new Database Administrator (DBA) might try to accomplish this by building a synchronization library or performing...