Expert Oracle Exadata - Parent Directory

CHAPTER 6 MAKING PCBSTable 6-1. Database Parameters Controlling 11gR2 Parallel FeaturesParameter Default Descriptionparallel_adaptive_multi_user TRUEparallel_automatic_tuning FALSEparallel_degree_limit CPUparallel_degree_policy MANUALparallel_execution_message_size 16384parallel_force_local FALSEparallel_instance_groupparallel_io_cap_enabled FALSEparallel_max_serversparallel_min_percent 0Old mechanism of throttling parallel statements bydowngrading. In most cases, this parameter shouldbe set to FALSE on Exadata, for reasons we’ll discusslater in the chapter.Deprecated since 10g. This parameter enabled anautomatic DOP calculation on objects for which aparallelism attribute is set.This parameter sets an upper limit on the DOP thatcan be applied to a single statement. The defaultmeans that Oracle will calculate a value for this limitbased on the system’s characteristics.Controls several parallel features includingAutomatic Degree of Parallelism (auto DOP), ParallelStatement Queuing and In-memory ParallelExecution.The size of parallel message buffers in bytes.Determines whether parallel query slaves will beforced to execute only on the node that initiated thequery (TRUE), or whether they will be allowed tospread on to multiple nodes in a RAC cluster (FALSE).Used to restrict parallel slaves to certain set ofinstances in a RAC cluster.Used in conjunction with theDBMS_RESOURCE_MANAGER.CALIBRATE_IO function tolimit default DOP calculations based on the I/Ocapabilities of the system.The maximum number of parallel slave process thatmay be created on an instance. The default iscalculated based on system parameters includingCPU_COUNT and PARALLEL_THREADS_PER_CPU. On mostsystems the value will work out to be 20CPU_COUNT.Old throttling mechanism. It represents theminimum percentage of parallel servers that areneeded for a parallel statement to execute.144