DBMS_JOB and Oracle Scheduler share the same job coordinator and job slaves, and they are both controlled by the JOB_QUEUE_PROCESSES parameter.

If the value of JOB_QUEUE_PROCESSES is set to 0 in a non-CDB or in a CDB root, then DBMS_JOB jobs and Oracle Scheduler jobs will not run in the non-CDB or in the root.

If JOB_QUEUE_PROCESSES is set to a value in the range of 1 to 4000 in a non-CDB or in a CDB root, then DBMS_JOB jobs and Oracle Scheduler jobs will run. The actual number of job slaves created for Oracle Scheduler jobs is auto-tuned by the Scheduler depending on several factors, including available resources, Resource Manager settings, and currently running jobs. However, the combined total number of job slaves running DBMS_JOB jobs and Oracle Scheduler jobs on an instance can never exceed the value of JOB_QUEUE_PROCESSES for that instance.

In a multitenant container database (CDB) environment, JOB_QUEUE_PROCESSES in the CDB root indicates the absolute maximum number of total jobs allowed in the whole instance. In a PDB, the only valid values for JOB_QUEUE_PROCESSES are 0 and 4000, where 0 means that no jobs can be run in that PDB and 4000 means that jobs are allowed to run in that PDB..

Materialized views use Oracle Scheduler for automatic refreshes. Setting JOB_QUEUE_PROCESS to 0 will disable this feature and any other features that use Oracle Scheduler or DBMS_JOB.