u | querying multiple instances |
| simultaneously |
u | accessing any information in the |
| instance in any order |
u | cascading queries |
u | applying any condition at any point |
u | keep results of subqueries for later use
u | combining results of queries such as |
| union, intersection etc. |
u | result of the query can be anything |
| from single value to an entire tree |
u | optimizing performance by introducing |
| auxilliary data structures |