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- Another problem with range partitioning is that a join attribute may appear
a different number of times in different partitions.
- Eg. A relation R = {1,2,3,4,4,4,4,4,4,4,4,5} to be partitioned over 3
processors. An even partitioning vector
corresponds to [4,4]. Hence to balance the load evenly among the 3 processors,
1/8 of the tuples containing 4 as the join attribute (along with join attribute values 1,2,3) must be directed to P0, 1/2 of the tuples containing 4 must be
directed to P1, and 3/8 of the tuples containing 4 (along with join attribute
value 5) must be directed to P2.
- This is known as weighted range partitioning.
DBMS
1999-03-11