Stopping cascading logical replication

Question

Given two primary PG12 servers, A and B, let's setup logical replication from A to B.

A --> B

Both servers can and do receive writes, and don't use sequences or unique constraints so there is no conflict.

Is it possible to set up replication from B to A, without replicating the data replicated from A?

Writes from A: A --> B -x-> A

Writes from B: B --> A -x-> B

End result is both databases have the same data set.

Answer 1

No, that is not possible. Replication cannot be cyclical.

You seem to be looking for a multi-master solution for PostgreSQL, but there are no open source solutions for that.

If I get that right that you have no unique or primary key constraints on the table, logical replication will not do what you want if the table contains duplicate rows.