Enumeration of Plans (Contd.)
ORDER BY, GROUP BY, aggregates etc. handled as a final step, using either an `interestingly ordered’ plan or an additional sorting operator.
An N-1 way plan is not combined with an additional relation unless there is a join condition between them, unless all predicates in WHERE have been used up.
- i.e., avoid Cartesian products if possible.
In spite of pruning plan space, this approach is still exponential in the # of tables.