What is the maximum number of master nodes allowed in a PostgreSQL configuration considering replication and fault tolerance?

In the standard PostgreSQL configuration with replication, there is usually one master node (primary) that accepts writes, and several standby nodes that synchronize with the master. PostgreSQL does not support multiple active master nodes out of the box.

To implement high availability and scaling with multiple masters, external solutions such as Patroni, BDR (Bi-Directional Replication), or other clustering systems are used.

Therefore, the maximum number of master nodes in the standard configuration is 1. If multi-master replication is needed, it is achieved through third-party extensions and solutions that can support multiple active masters, but these are complex architectures with their own limitations and consistency requirements.