Configuring and Controlling 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. PARALLEL_DEGREE_POLICY This is the parameter used to enable/disable Auto DOP system-wise or session-wise.
Configuring and Controlling Auto DOP - Oracle
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. PARALLEL_DEGREE_POLICY This is the parameter used to enable/disable Auto DOP system-wise or session-wise.
Setting the Degree of Parallelism - Oracle Help Center
Controlling Automatic Degree of Parallelism Adaptive Parallelism 8.2.1 Manually Specifying the Degree of Parallelism A specific degree of parallelism (DOP) can be requested from Oracle Database for both tables and indexes. For example, you can set a fixed DOP at a table level with the following:
Parallel Execution With Oracle Database 12c - Masterclass
The problem with manual DoP Limited resources One size fits all does not work well Critical statements may run serially due to not enough available PX servers Manual tuning is needed to determine DoP No way to increase DoP of running statements 72 73. Auto DoP Optimizer’s estimates decides whether SQL should run in
About Initializing and Tuning Parameters for Parallel Execution
Controls the maximum DOP a statement can have when automatic DOP is in use. The maximum DOP is . SUM(CPU_COUNT)*PARALLEL_THREADS_PER_CPU. The value AUTO for PARALLEL_DEGREE_LIMIT has the same functionality as the value CPU. PARALLEL_DEGREE_POLICY. MANUAL. Controls whether auto DOP, parallel statement queuing and in-memory parallel execution are
- 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.
- 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 to enable/disable Auto DOP in SQL Server?
- 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. This is the parameter used to enable/disable Auto DOP system-wise or session-wise.
- How does auto DOP work with parallel statement queuing & database resource manager?
- Auto DOP relieves the burden of deciding on a DOP for each statement and enables you to focus on optimizing the whole workload together with Parallel Statement Queuing and Database Resource Manager. We will talk about how these work together in later posts.
- 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.
