PostgreSQL 12 High Availability Cookbook - Third Edition

Picking redundant copies

How many database servers should any architecture have as part of the inherent design? There are several factors that contribute to this answer, including the design of the final architecture itself. The number of redundant data copies ultimately determines how many nodes must exist, irrespective of whether we require more data centers, irrespective of whether we should account for latency, and so on.

The goal in this recipe is to consult our needs to derive a node count that won't break the bank, but still deliver the level of availability we want. In other words, aside from our primary data node, we will explain how to figure out the number of redundant data nodes necessary to adequately represent the entire cluster ...