----------------------- ----------------------- | rcu Customer | cus_s | rfl Group | |=====================|--------------------------------------------------------->|=====================| | cus_s: customer | | cus_s: customer | ----------------------- | grp_s: group | | | ----------------------- | | | | | ----------------------- | | | cus_s | ral Lessee | | | +---------->|=====================| | | | les_s: lessee | | | | cus_s: customer | | | ----------------------- | | | | | | | | | ----------------------- | | | les_s | rls Lease | | | +------------>|=====================| | | cus_s | lse_s: lease | cus_s, grp_s | +---------------------------------------->| les_s: lessee |<-------------------+ | cus_s: customer | | grp_s: group | -----------------------
All leases in a group belong to the same lessee.
A join with the rls table on rls.cus_s or rls.cus_s/rls.grp_s is non-indexed and requires a search of the entire rls table.