> Postgres has a different issue in that replication slots can grow really fast, esp on AWS! [2]. We ended up writing our own custom snapshotter for Postgres that is Debezium compatible to onboard customers that have a massive dataset and cannot afford to have a read lock on their WAL.

Does Debezium's DDD-3 watermark (DBLog) implementation for Postgres not process the WAL quickly enough? We don't use it ourselves either, but architecturally it appears it would reasonably bound how long the WAL can remain un-read?

Agreed that many production DBs people care about have pretty severe limitations here! Managed Supabase is another good example.