Partition-wise Joins

A partition-wise join is a join optimization for joining two tables that are both
partitioned along the join column(s). With partition-wise joins, the join operation is
broken into smaller joins that are performed sequentially or in parallel. Another way
of looking at partition-wise joins is that they minimize the amount of data exchanged
among parallel slaves during the execution of parallel joins by taking into account data
distribution.[@more@]