Journal planning for logical replication

If you are using logical replication, you should use journaling to force writes from the production copy of data to the backup copy of data.

Journal management prevents transactions from being lost if your system ends abnormally. When you journal an object, the system keeps a record of the changes you make to that object. Regardless of the high availability solution that you implement, journaling is considered a best practice to prevent data loss during abnormal system outages.

In logical replication environments, journaling is the basis of the solution and as such is a requirement for implementing a solution based on this technology. With logical replication, a real-time copy to a backup system might be limited depending on the size of the object being replicated. For example, a program updates a record residing within a journaled file. As part of the same operation, it also updates an object, such as a user space, that is not journaled. The backup copy becomes completely consistent when the user space is entirely replicated to the backup system. Practically speaking, if the primary system fails, and the user space object is not yet fully replicated, a manual recovery process is required to reconcile the state of the user space to match the last valid operation whose data was completely replicated.