Highly available Postgres with Patron 3.0 and Citus
published on 2023/03/08
Patroni 3.0 brings official Citus support to Patroni. While it was already possible to run Patroni with Citus before Patroni 3.0 (due to the flexibility and extensibility of Patroni!), the 3.0 release has made the integration with Citus for HA much better and easier to use.
Patroni is relying on DCS to discover nodes of the PostgreSQL cluster and configure streaming replication. As already explained in the “Terminology clarification” section, the Citus cluster is just a bunch of PostgreSQL clusters that are logically connected using Citus extension to Postgres. Hence, it was logical to extend Patroni so it could discover not only nodes of the given Patroni/PostgreSQL cluster, but also discover nodes in a Citus cluster, such as when a new Citus worker node has been added. As Citus nodes are discovered, they are added to the Citus coordinator pg_dist_node metadata.
This is fantastic