Database Reference
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Figure 14-13. Joining two partitioned tables without a partition-wise join
When the two tables are equi-partitioned on their join keys (for example, a child table that is reference-partitioned
based on the foreign key to its parent table), the database engine is able to take advantage of a full partition-wise join.
Instead of executing a single large join, it performs, as shown in Figure 14-14 , several smaller joins (in this case, four).
Note that this is possible because the tables are partitioned in the same way. Because of this, every row that is stored in,
for example, partition 1 of table 1 can have matching rows only in partition 1 of table 2.
Figure 14-14. Joining two tables with a full partition-wise join
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