Equality
Joins With One Join Column
•R S is a common operation. The cross
product is too large. Hence, performing R S
and then a selection is too inefficient.
•Assume: M pages in R,
pR tuples per page, N pages in S, pS tuples per page.
–In our
examples, R is Person and S is Purchase.
•Cost metric: # of I/Os. We will ignore output costs.
SELECT
*
FROM Person
R, Purchase S
WHERE
R.name=S.buyer
JOIN