Recommended Approach for Instanced Content

The realtime parts of my game are highly instanced (instances or raid in WoW, matches in Fortnite/DotA/etc). What is the recommended approach to do that with spacetime db?

I see two options, instance IDs or db for each instance.

With instance ids, we'd add a instance_id column to every table that has instances content. We'd have to create indexes and pollute many queries with WHERE instance_id = ?. It might also have difficulty scaling at some point.

With multiple DBs, we'd init a new DB for each instance and shut it down after the match is over. This might have a high cost for startup and shutdown. It also might not easily support replays or other innate features well.

Which would the creators of the system or expert users recommend?