Select /*+parallel(tab n)*/ from tab; Alter session force parallel query parallel n; 如果没有设置将执行默认并行度 3. 默认并行度 单实例 = PARALLEL_THREADS_PER_CPU x CPU_COUNT RAC = PARALLEL_THREADS_PER_CPU x CPU_COUNT x INSTANCE_COUNT SQL> show parameter parallel NAME TYPE VALUE --- ...
cpu_count integer 2 parallel_threads_per_cpu integer 2 cpu_count表示cpu数 parallel_threads_per_cpu表示每个cpu允许的并行进程数 default情况下,并行数为cpu_count*parallel_threads_per_cpu 取消并行设置 SQL> alter table t1 noparallel; SQL> select degree from user_tables where table_name='T1'; DEGREE...
parallel_threads_per_cpu integer 2 cpu_count表示cpu数 parallel_threads_per_cpu表示每个cpu允许的并行进程数 default情况下,并行数为cpu_count*parallel_threads_per_cpu 2.取消并行设置 SQL> alter table t1 noparallel; SQL> select degree from user_tables wheretable_name='T1'; DEGREE --- 1 3.数据字...
//workerThreads线程池中辅助线程的最大数目,completionPortThreads线程池中异步I/O线程的最大数目 ThreadPool.GetMaxThreads(out workerThreads, out completionPortThreads); //workerThreads线程池根据需要创建的最少数量的辅助线程 //completionPortThreads线程池根据需要创建的最少数量的异步I/O线程 ThreadPool.GetMin...
最近的MySQL8.0.14版本增加了其第一个并行查询特性,可以支持在聚集索引上做SELECT COUNT()和check table操作。本文简单的介绍下这个特性。 用法 增加了一个session级别参数:innodb_parallel_read_threads 要执行并行查询,需要满足如下条件(ref:row_scan_index_for_mysql) ...
Alter session force parallel query parallel n;如果没有设置将执⾏默认并⾏度 3. 默认并⾏度 单实例 = PARALLEL_THREADS_PER_CPU x CPU_COUNT RAC = PARALLEL_THREADS_PER_CPU x CPU_COUNT x INSTANCE_COUNT SQL> show parameter parallel NAME TYPE VALUE --- --- --- fast_start_parallel_rol...
4、数决定SQL show parameter cpuNAMETYPE VALUEcpu_countinteger 2parallel_threads_per_cpu integer 2cpu_count表示cpu数parallel_threads_per_cpu表示每个cpu允许的并行进程数default情况下,并行数为cpu_count*parallel_threads_per_cpu2.取消并行设置SQL alter table t1 noparallel;SQL select degree from user_table...
I am trying to read evtx logs from different machines using EvtQuery API. Each thread will be querying a machine in parallel. But I can observe that all the threads are blocked when the EvtQuery API is called due to an internal critical section wait.…
After exchange operators are inserted, the result is a parallel-query execution plan. A parallel-query execution plan can use more than one thread. A serial execution plan, used by a nonparallel query, uses only one thread for its execution. The actual number of threads used by a parallel ...
Because this plan has two exchange segments, with degree of parallelism equal to 4, it uses eight threads. See Also Concepts Parallel Query Processing English (United States) Your Privacy Choices Theme Manage cookies Previous Versions Blog Contribute Privacy Terms of Use Trademarks © ...