We have successfully configured logical replication between a primary metadata DB and a replica UI DB. Out of curiosity, what types of extra data is the Metaflow UI writing to the logical replica that we otherwise don’t want in the primary? Or is it just the case that the UI adds a lot of extra load to the primary DB?

it doesn’t do a lot of writes. the only reason for the replica is to avoid interfering with main db (to avoid any issues). It does need to be a logical replica and not a read replica though because the UI “writes” things indicating it wants to be informed of certain events (so it can “listen” for updates).

The UI in this context means 1. A browser side web app, or 2. A service task (i.e., an ECS task in our case) ?

the UI is the service task I guess. It’s whatever is running the UI server that you connect to from your browser. It’s the one making the connections to the db.