Bi-Directional Logical Replication in PostgreSQL 16
published on 2023/12/19
Logical replication has been supported since PostgreSQL 10 and has received numerous updates and improvements in the following years. Logical Replication is the process of copying (ie. replicating) data objects represented as their changes. This way we can copy only specific changes of objects like tables rather than whole databases, and stream these changes across different platforms and versions. This is all in contrast to Physical replication which uses exact block addresses and as a result, is limited to only copying entire databases and cannot stream across platforms or versions since the data must match in both.
Now that we understand what Logical Replication is, what is Bi-Directional Replication doing differently? In short, Bi-Directional Logical Replication is when all nodes in the replication are both Publisher and Subscriber. Each database can now handle read and write requests, and all the changes will be streamed to one another. This is the Bi-Directional aspect, as rather than changes flowing in one direction as before, they flow in both directions