Doesn't same database multi-tenancy defeats the one-tenant one-database advantage of being able to easily disaster recover a single tenant or allow for easily moving a tenant and all their stuff to a dedicated box?
So there will be a cost per dB A cost to backup that dB Etc
And so a lot of companies, particularly startup, will keep one large dB.
For example, you generally only want to have one tenant’s data per storage page. There are many famous ways that interleaving different tenants’ data at a fine-grained level can go very wrong.
There are also advantages from a cache utilization standpoint if the system is heavily loaded.
I understand there are potential regulatory concerns with this, but I've never seen an audit get even remotely close to this level of detail.