Semab Tariq provides some high-level guidance:
In today’s digital landscape, downtime isn’t just inconvenient, it’s costly. No matter what business you are running, an e-commerce site, a SaaS platform, or critical internal systems, your PostgreSQL database must be resilient, recoverable, and continuously available. So in short
High Availability (HA) is not a feature you enable; it’s a system you design.
In this blog, we will walk through the important things to consider when setting up a reliable, production-ready HA PostgreSQL system for your applications.
Click through for a variety of things to think about. Most of this will apply to other database systems as well, though specific tools will differ.