Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
OCA /OCP Oracle Database 11g A ll-in-One Exam Guide- P86:There is an ever increasing demand for staff with IT industry certification. The benefits to employers are significant—they can be certain that staff have a certain level of competence—and the benefits to the individuals, in terms of demand for their services, are equally great. Many employers are now requiring technical staff to have certifications, and many IT purchasers will not buy from firms that do not have certified staff. | OCA OCP Oracle Database 11g All-in-One Exam Guide 806 There will be many occasions when you as DBA or your users need to automate the scheduling and running of jobs. These jobs could be of many kinds for example maintenance work such as database backups data loading and validation routines report generation collecting optimizer statistics or executing business processes. The Scheduler is a facility that can be used to specify tasks to be run at some point or points in the future. The jobs can run within the database on the machine hosting the database instance or even on a remote machine. The Scheduler can be coupled to the Resource Manager. It can activate Resource Manager plans and run jobs with the priorities assigned to various Resource Manager consumer groups. The Scheduler was introduced in release 10g of the Oracle database and is substantially enhanced in release 11g. In earlier releases of the database job scheduling capabilities were provided through the DBMS_JOB facility. This is still supported for backward compatibility but it is not as versatile as the Scheduler. The Scheduler Architecture The data dictionary includes a table that is the storage point for all Scheduler jobs. You can query this table through the DBA_SCHEDULER_JOBS view. The job queue coordinator background process the CJQ0 process monitors this table and when necessary launches job queue processes the Jnnn processes to run the jobs. The CJQ0 process is launched automatically if there are any defined and active Scheduler jobs. The Jnnn processes are launched on demand though the maximum number is limited by the JOB_QUEUE_PROCESSES instance parameter which can have any value from zero to a thousand the default . If set to zero the Scheduler will not function. The job queue coordinator picks up jobs from the job queue table and passes them to job queue processes for execution. It also launches and terminates the job queue processes on demand. To see the processes currently running query .
