Exploring versions of the Postgres logical replication protocol

Logical Replication is a feature in Postgres that allows databases to replicate data to other Postgres databases or ETL tools like PeerDB. It has evolved over time, with newer versions offering improvements such as streaming of large in-progress transactions and parallel apply of in-flight transactions. The latest version 4 supports spreading out the load of applying a single large transaction over multiple processes in the standby. By using version 2 to stream in-flight transactions, users can efficiently manage WAL spikes during sizable transactions, enhancing logical decoding performance and mitigating disk full issues caused by replication slot growth. This approach reduces the lag between the Postgres source and its readers, improving overall reliability and performance.