PARALLEL INSTANCE GROUP

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Test Case #2: Bounded Test. To restrict parallel processing to specific cluster nodes, instance groups are employed to create logical server groupings. Control is via the INIT.ORA with the parameter INSTANCE_GROUPS. INSTANCE_GROUPS is a RAC-related parameter that is specified only in parallel mode. Used in conjunction with the runtime parameter PARALLEL_INSTANCE_GROUP, it allows for the restriction of parallel query operations to a limited number of instances.

For the tests in this section, the INSTANCE_GROUPS identified below will be utilized.


  1. Init.ora Parameter Setting for Parallel Options

SALES1.INSTANCE_GROUPS='marketing' SALES2.INSTANCE_GROUPS='finance'


The session below is altered prior to the execution of the query to be assigned to the FINANCE group. Even though the query is initiated on the SALES1 node, based on the INSTANCE_GROUP setting all of the processing will be executed on SALES2.


alter session set parallel_instance_group = 'finance';

select /*+ full(c_stock) parallel(c_stock,6) */ sum(s_quantity) odcnt from c_stock /


Note in the process listing that all of the parallel workers requested are indeed run only on the SALES2 node, as there is no CPU time being utilized by the processes on SALES1.


UID PID PPID C STIME TTY TIME CMD oracle 29994 1 0 14:13 ? 00:00:00 ora_p000_SALES1 oracle 29996 1 0 14:13 ? 00:00:00 ora_p001_SALES1

oracle 2631 1 0 14:51 ? 00:00:01 ora_p000_SALES2 oracle 2633 1 0 14:51 ? 00:00:01 ora_p001_SALES2 oracle 2676 1 4 14:57 ? 00:00:01 ora_p002_SALES2 oracle 2678 1 3 14:57 ? 00:00:01 ora_p003_SALES2 oracle 2680 1 4 14:57 ? 00:00:01 ora_p004_SALES2