Problem Description

BigAnimal offers a complete High Availability(HA) cluster in the cloud managed by EDB.
Some customers may need to establish logical replication between the BigAnimal HA cluster and some Postgres instance on premises or hosted by some public cloud provider.

Due to a specific Postgres limitation, this is currently not possible.

Postgres implements logical replication using logical replication slots, a mechanism to ensure that transactional logs (WAL files) are not discarded by the primary server before they are applied in the replica.

In a high availability system when a failover or switchover occurs the logical replication slots cannot fail or switch over and this impedes the replication for resuming.

So, promoting a secondary Postgres cluster will break logical replication.

Solution

To be able to establish a logical replication from a BigAnimal cluster and a Postgres cluster hosted on premises or at some public cloud provider, it is necessary to create a BigAnimal single node cluster.
It is important to note that in the event of maintaining a single node cluster, some service interruption may occur.