DB2® Version 8: The Official Guide

New Join Variations

DB2 UDB v8.1.2 introduces three new join variations to the current run-time joins. They are:

• Reverse outer join (or right outer join)— an outer join that has the inner table as the row preserving side.

• Reverse early out— an inner join that a tuple of the inner table only need to match the first matched tuple of the outer table.

• Anti join— an outer join that returns only tuples from the row preserving side (can be either inner table or outer table) that have no match to tuples from the null producing side.

The new variations are exposed from various Explain tools via two existing flags: outer join flag and early out flag.