Re: Separating DBs
It is exceptionally hard to hyper-scale a SaaS system where each client has a unique single-tenant database. You get problems with backups taking very much longer, CDP with large numbers of databases, product upgrades which involve schema changes, load scaling across multiple product releases because you can't role out schema changes quick enough, etc etc. It's expensive to manage.
Multi-tenant solves many of these problems, but the trade-off is security. When you screw up, you screw up big-time.