----------------------- -----------------------
| 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.