A partitioned PI not only helps in retrieval from a single table, but it also helps when joining PPI tables. Direct merge joins of two PPI tables are available as an optimizer choice when the tables have:
- The same PI and identical partitioning expressions
- All PI columns and all partitioning columns specified as equality join terms
- A row-key based merge join
- Identical performance characteristics for row-key based merge joins and traditional merge joins
- A direct merge join, in the traditional sense, is not available when one table is partitioned and the other table is not, or when both tables are partitioned, but not in the same manner
Delayed partition elimination is when the partitioning column values are not known until ...
