PARALLEL_GBH_UNITS option

Overrules the choice of the optimizer on the degree of parallelism of GROUP BY operations.

0 – 100

0

Can be set temporary, for an individual connection, or for the PUBLIC group. Takes effect immediately.

When the PARALLEL_GBH_ENABLED option is ON, you can constrain the effect of this feature by changing the value of the PARALLEL_GBH_UNITS option. The PARALLEL_GBH_UNITS option overrules the optimizer’s choice on the degree of parallelism. Normally, you should not set this option.

The argument to PARALLEL_GBH_UNITS is a value that represents a specific number of parts to break the GROUP BY into in order to execute in parallel. For example, to run in eight parts, use

SET TEMPORARY OPTION PARALLEL_GBH_UNITS = 8

If PARALLEL_GBH_UNITS is 0, the optimizer chooses the degree of parallelism based on the number of CPUs, the number of users on the server, and the amount of data to be grouped.