high purity Configuring and Controlling Auto DOP

  • high purity Configuring and Controlling Auto DOP
  • high purity Configuring and Controlling Auto DOP
  • high purity Configuring and Controlling Auto DOP
  • How to configure and control auto DOP?
  • Now, let's look at how you can configure and control Auto DOP. There are two ways to enable/disable Auto DOP, you can enable/disable it for the whole system or for a session using the initialization parameter parallel_degree_policy, or you can enable/disable it for specific SQL statements using hints.
  • What happens if I enable auto DOP?
  • With Auto DOP since the optimizer is deciding when to use parallel execution and the DOP to use, depending on how you configure Auto DOP, the number of parallel statements and their DOPs may change when you enable it. Some serial statements may start running in parallel, some parallel statements may start running serially.
  • How to enable auto DOP in JavaScript?
  • Auto DOP is enabled by setting the PARALLEL_DEGREE_POLICY parameter. Allowable values are as follows. MANUAL : (DEFAULT) Disables auto DOP, statement queuing and in-memory parallel execution. Resembled pre-11.2 behaviour. LIMITED : Enables auto DOP for statements against objects with parallel settings.
  • What is auto DOP vs manual DOP?
  • As opposed to manual DOP it does not require table/index decorations or hints. Here is the basic decision flow for a SQL statement with Auto DOP. The optimizer first generates a serial plan for the SQL statement and estimates the execution time. If the estimated execution time is less than the specified threshold the statement runs serially.
  • How do I limit the DOP computed by the optimizer with auto DOP?
  • The DOP computed by the optimizer with Auto DOP can be quite high depending on the resource requirements of the statement. You can limit the DOP using the initialization parameter parallel_degree_limit or Database Resource Manager (DBRM). This parameter limits the DOP that can be computed by the optimizer.
  • What is the default DOP value?
  • The default value of this parameter is CPU which means the maximum DOP you can get is the default DOP which is parallel_threads_per_cpu * SUM (cpu_count). Even if you increase this parameter's value to be higher than the default DOP, the optimizer will always limit the DOP at default DOP.

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