PostgreSQL 12 High Availability Cookbook - Third Edition

How it works...

If we have an existing database, there is a wealth of statistical information at our fingertips. The first query we ran gave us a slightly inflated count of PostgreSQL replicas. For each replica, data must be transferred from the database to another server. This data is based on PostgreSQL WAL output, and these files are 16 MB each. A busy server can produce more than ten of these per second, so we multiply the count of streams by 160 to produce an aggressive amount of network overhead used by database replicas. As usual, this may be overzealous; it's always best to observe an actual system to measure maximum WAL segments generated during heavy write loads.

In PostgreSQL 9.2 and higher, database replicas can stream from other ...