In the implementation of hosted business services, multi-
ple tenants are often consolidated into the same database
to reduce total cost of ownership. Common practice is to
map multiple single-tenant logical schemas in the applica-
tion to one multi-tenant physical schema in the database.
Such mappings are challenging to create because enterprise
applications allow tenants to extend the base schema, e.g.,
for vertical industries or geographic regions. Assuming the
workload stays within bounds, the fundamental limitation
on scalability for this approach is the number of tables the