oracle job 没自动运行 JOB_QUEUE_PROCESSES

之前运行好好的Job突然停掉了，后来想想原来是修改数据字符集的时候，把JOB_QUEUE_PROCESSES设为0啦

重新改回来

alter system set job_queue_processes = 20 scope=both;

oracle文档关于JOB_QUEUE_PROCESSES的说明

JOB_QUEUE_PROCESSES specifies the maximum number of processes that can be
created for the execution of jobs. It specifies the number of job queue processes per
instance (J000, ... J999). Replication uses job queues for data refreshes. Advanced
queuing uses job queues for message propagation. You can create user job requests
through the DBMS_JOB package.
Some job queue requests are created automatically. An example is refresh support for
materialized views. If you wish to have your materialized views updated
automatically, you must set JOB_QUEUE_PROCESSES to a value of one or higher.