The subquery execution method SQL optimization specification allows you to specify a subquery execution method for a subquery that occurs in a predicate.

Subquery-execution-method-SQL-optimization-specification:: = {HASH|NO HASH}

• {HASH|NO HASH}

HASH

Specifies the option for making the subquery execution method into a hash execution.

NO HASH

Specifies the option for making the subquery execution method into a non-hash execution.

1. Subquery execution method SQL optimization specification should be specified in a subquery that occurs in a predicate.
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-execution, see the HiRDB Version 8 UAP Development Guide.

1. For subquery execution methods, see the subquery execution method without external reference or the subquery execution method with external reference in the HiRDB Version 8 UAP Development Guide. Subquery execution methods can be checked by using the access path display utility.