=== with the schema's indexes
queue of one outlet:
    SEARCH Bill USING INDEX Bill_outlet_status_idx (Outlet_id=? AND status=?)
one bill by its id:
    SEARCH Bill USING INDEX sqlite_autoindex_Bill_1 (id=?)
customer by phone:
    SEARCH Customer USING INDEX Customer_phone_idx (phone=?)
customer by phone digits:
    SCAN Customer
bills of March, by range:
    SEARCH Bill USING COVERING INDEX Bill_arrived_idx (arrived>? AND arrived<?)
bills of March, by SUBSTR:
    SCAN Bill USING COVERING INDEX Bill_arrived_idx

=== without them (14 indexes dropped)
queue of one outlet:
    SCAN Bill
one bill by its id:
    SEARCH Bill USING INDEX sqlite_autoindex_Bill_1 (id=?)
customer by phone:
    SCAN Customer
customer by phone digits:
    SCAN Customer
bills of March, by range:
    SCAN Bill
bills of March, by SUBSTR:
    SCAN Bill

