SELECT R.bFROM R,S,TWHERE R.a = S.a and S.b = T.b;

SELECT R.bFROM R,S,TWHERE R.a = S.a and S.b = T.bORDER BY R.b ;

Joins vs. Plans (Interesting orders)

T T.bDC

RS S.bDC

DC R.aR

S.aDC S.bS

ST S.aDC

RST DC

In-memory directory

Number of Joins = 4Number of Plans = 1215

R.b

R.b

R.b

R SS T

R ST

RS T

2 join partitions

Order on R.a is interesting (useful) for Merge-join with S