Some apps now need PostgreSQL logical replication. The one I've hit is wger: since version 2.0, its mobile app requires PowerSync, which reads changes from the wger database through a logical replication slot. PowerSync, ElectricSQL, Supabase Realtime, Zero and Debezium all work this way.
The addon currently can't support this. The server runs with wal_level=replica, and app roles don't have the REPLICATION attribute. Neither can be changed from inside a package, so the only option is to bundle a separate PostgreSQL in the app and give up the addon's managed backups and upgrades.
Would you consider an opt-in addon option, something like "postgresql": { "logicalReplication": true }? It would need to:
run the server with wal_level=logical (the only cost to other apps is somewhat more write-ahead log (WAL) volume)
grant REPLICATION to the role of each app that asks for it
set max_slot_wal_keep_size, so an abandoned slot can't fill the shared disk
drop the app's replication slots on uninstall and before a restore
With that, packages like wger could stay on the addon instead of each shipping its own database.
