The join method SQL optimization specification allows you to specify a join method for a joined table.

Join-method-SQL-optimization-specification::= BY {NEST|HASH|MERGE}

• {NEST|HASH|MERGE}

NEST

This option can be specified to make the join method into either a nest-loop-join or a distributed nest-loop-join.

The result is a nest-loop-join if the inner table is a base table or a named derived table based on the base table; it is a distributed nest-loop-join if the inner table is an outer table or a named derived table based on the outer table.

HASH

This option can be specified when making the join method into a hash-join.

MERGE

This option can be specified when making the join method into a merge-join.

1. When specified for a join that is executed on a foreign server, the SQL optimization specification is nullified.
2. Specifying HASH requires the same preparations as specifying execution of a hash-join or a subquery hash for the SQL extension optimizing option. For preparations for applying either hash-join or subquery-hash-join, see the HiRDB Version 8 UAP Development Guide.

1. For join methods, see the HiRDB Version 8 UAP Development Guide. Join methods can be checked by using the access path display utility.