IMPLICIT_PDQ Environment Option (XPS)

Use the IMPLICIT_PDQ environment option to allow the database server to determine the amount of memory allocated to a query. Unless BOUND_IMPL_PDQ is also set, the database server ignores the current explicit setting of PDQPRIORITY. It does not allocate more memory, however, than is available when PDQPRIORITY is set to 100, as determined by MAX_PDQPRIORITY / 100 * DS_TOTAL_MEMORY.

This environment option is OFF by default.

If you set value between 1 and 100, the database server scales its estimate by the specified value. If you set a low value, the amount of memory assigned to the query is reduced, which might increase the amount of query-operator overflow.

For example, to request the database server to determine memory allocations for queries and distribute memory among query operators according to their needs, enter the following statement:

SET ENVIRONMENT IMPLICIT_PDQ ON

To require the database server to use explicit PDQPRIORITY settings as the upper bound and optional lower bound of memory that it grants to a query, set the BOUND_IMPL_PDQ environment option.