•The optimizer can use any semantically correct rule to transform one query to another.
•Rules try to:
–move constraints between blocks (because each will be
optimized separately)
–Unnest blocks
•Especially important in decision support applications where queries are very complex.
•In a few minutes of thought, you’ll come up with your
own rewrite. Some query,
somewhere, will benefit from it.
•Theorems?
•