Placeholder text for a post on Postgres logical replication. The plan is to start with the basics — publications, subscriptions, and how they differ from streaming (physical) replication — before getting into where things actually go wrong.
A middle section will cover schema changes: what happens to a subscription when a column is added upstream, and why DDL isn’t replicated automatically.
The last part will probably be a short case study on replication lag, including which system views to check first (pg_stat_replication, pg_replication_slots) when a subscriber starts falling behind.