SELECT R.b

1
Joins vs. Plans (Interesting orders)
In-memory directory

• SELECT R.b
• FROM R,S,T
• WHERE R.a S.a and
• S.b T.b

SELECT R.b FROM R,S,T WHERE R.a S.a and
S.b T.b ORDER BY R.b
Number of Joins 4 Number of Plans 12
15
Order on R.a is interesting (useful) for
Merge-join with S