How to Monitor PostgreSQL Changes with Write-Ahead Logging

The article delves into the limitations of using pg_notify for listening to database changes in PostgreSQL, particularly in high-transaction environments where it can create bottlenecks. It then introduces the concept of the Write-Ahead Log (WAL), explaining how it captures every change in the database, allowing for more efficient and robust systems. The write-up covers the setup of PostgreSQL to store logical WAL records, the creation of publications and replication slots, and finally provides a detailed implementation of a WAL listener in Elixir. Throughout the article, the benefits of using the WAL for Change Data Capture (CDC) and real-time notifications are emphasized, along with code snippets for practical application.