The join method SQL optimization specification allows you to specify a join method for a joined table.
(2) Format
Join-method-SQL-optimization-specification::= BY {NEST|HASH|MERGE}
(3) Operands
{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.
(4) Rules
When specified for a join that is executed on a foreign server, the SQL optimization specification is nullified.
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.
(5) Notes
For join methods, see the HiRDB Version 8 UAP Development Guide. Join methods can be checked by using the access path display utility.