Query Optimization

Imperative query execution plan:

SELECT S.sname

FROM Reserves R, Sailors S

WHERE R.sid=S.sid AND

R.bid=100 AND S.ratingɱ

Declarative SQL query

Plan: Tree of Relational Algebra operators,

with a choice of algorithm implementation for each operator

Ideally: Want to find best plan. Practically: Avoid worst plans!

Goal:

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