> Because essentially what’s happening with database per user is that we don’t keep anything in memory for users who are inactive, or only active on another ins

> Because essentially what’s happening with database per user is that we don’t keep anything in memory for users who are inactive, or only active on another instance, for essentially the same schema (or maybe a couple versions of a schema). The benefits of prefetching and page-level abstractions are certainly reduced when every tenant is guaranteed to live in a different file. I would agree that you should have to deal with an uphill battle when arguing for a DB-per-customer architecture. There needs to be a special reason to not simply add a customer/tenant id column in each table. I think one good argument for placing a tenant per database file is that it makes total destruction of their information possible without any impact to other tenants. If you don't require immediate destruction of the tenant's information (i.e., can wait for background cleanup activities), then I would begin to push back.