Joins vs. Plans (Interesting orders)

1. RST DC R.b 2 join partitions ST S.a DC R RS R S T T S ST S.b RS DC R.b T.b DC T S S.b S.a DC R R.b DC R.a 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