It’s an interesting idea, but how would such a system handle queries that should cross tenant boundaries? (E.g. system-level reporting)
2. I have had good luck using pragma comments for that kind of thing: a way to communicate to the infrastructure without the target system seeing it
3. From the "malicious compliance department," I would also accept "include it but in a tautological way" (tenant_id = :ten_id or tenant_id <> :ten_id)