Lemmy Federation - 0.17.4 era - does the home instance for the community send all outbound messages? Is it a hub for the community?

I find it interesting that the PostgreSQL comment table in Lemmy has no concept of which instance the comment came from, nor does it have local flag. Well, a comment row does have the ap_id field, but it is in a format that doesn't really allow you to sort trivially by origin-instance.