oracle手册解释

FAST_START_PARALLEL_ROLLBACK determines the maximum number of processes that can exist for performing parallel rollback. This parameter is useful on systems in which some or all of the transactions are long running.

Values:

FALSE indicates that parallel rollback is disabled

LOW limits the number of rollback processes to 2 * CPU_COUNT

HIGH limits the number of rollback processes to 4 * CPU_COUNT
系统默认：SQL> show parameter fast_start_parallel_rollback;

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
fast_start_parallel_rollback string LOW
今天突然出现很多并行进程，搞得系统IDLE急剧下降。手册上指出当这个值是LOW,rollback的进程数就是2*cpu个数，而我的系统中正好是LOW，CPU正好是32个，那么就是64个进程了。
可是又是什么引起rollback呢，并且还要rollback这么多这么久？应该是有人做了批量DML，然后rollback了。

ITPub博客

参数FAST_START_PARALLEL_ROLLBACK(ZT)

最新文章