Query Execution Plans
Purchase
Person
Buyer=name
City=‘seattle’
phone>’5430000’
buyer
(Simple Nested Loops)
SELECT
S.sname
FROM Purchase P, Person Q
WHERE P.buyer=Q.name AND
Q.city=‘seattle’ AND
Q.phone
> ‘5430000’
s
Query
Plan:
• logical tree
• implementation choice at every node
• scheduling of operations.(Table scan)
(Index scan)
Some operators are from relational
algebra, and others (e.g., scan,
group)
are not.