Query Rewrite: Predicate Move-around

Create View V1 AS

Select rating, Min(age)

From Sailors S

Where S.age < 20

GroupBy rating

Create View V2 AS

Select sid, rating, age, date

From Sailors S, Reserves R

Where R.sid=S.sid, and

S.age < 20.

Select sid, date

From V1, V2

Where V1.rating = V2.rating and

V1.age = V2.age, and V1.age < 20

Sailing wizz dates: when did the youngest of each sailor level rent boats?

First, move

predicates up the

tree.

Then, move them

down.