Scheduler in Oracle Database 10g
Oracle 10g includes a comprehensive scheduler (DBMS_SCHEDULER) to replace and extend the functionality provided by the
DBMS_JOB package. Jobs form the core of the functionality, but there are several other components available:
- Programs
- Schedules
- Jobs
- Job Classes
- Windows
- Windows Groups
- Enable, Disable and Attributes
Programs
The scheduler allows you to optionally create programs which hold metadata about a task, but no schedule information. A program may related to a PL/SQL block, a stored procedure or an OS executable file. Programs are created using theCREATE_PROGRAM procedure:
-- Create the test programs.
BEGIN
-- PL/SQL Block.
DBMS_SCHEDULER.create_program (
program_name => 'test_plsql_block_prog',
program_type => 'PLSQL_BLOCK',
program_action => 'BEGIN DBMS_STATS.gather_schema_stats(' 'SCOTT' '); END;',
enabled => TRUE,
comments => 'Program to gather SCOTT' 's statistics using a PL/SQL block.');
-- Shell Script.
DBMS_SCHEDULER.create_program (
program_name => 'test_executable_prog',
program_type => 'EXECUTABLE',
program_action => '/u01/app/oracle/dba/gather_scott_stats.sh',
number_of_arguments => 0,
enabled => TRUE,
comments => 'Program to gather SCOTT' 's statistics us a shell script.');
-- Stored Procedure with Arguments.
DBMS_SCHEDULER.create_program (
program_name => 'test_stored_procedure_prog',
program_type => 'STORED_PROCEDURE',
program_action => 'DBMS_STATS.gather_schema_stats',
number_of_arguments => 1,
enabled => FALSE,
comments => 'Program to gather SCOTT' 's statistics using a stored procedure.');
DBMS_SCHEDULER.define_program_argument (
program_name => 'test_stored_procedure_prog',
argument_name => 'ownname',
argument_position => 1,
argument_type => 'VARCHAR2',
default_value => 'SCOTT');
DBMS_SCHEDULER.enable ( name => 'test_stored_procedure_prog');
END;
/
PL/SQL procedure successfully completed.
-- Display the program details.
SELECT owner, program_name, enabled FROM dba_scheduler_programs;
OWNER PROGRAM_NAME ENABL
------------------------------ ------------------------------ -----
SYS PURGE_LOG_PROG TRUE
SYS GATHER_STATS_PROG TRUE
SYS TEST_PLSQL_BLOCK_PROG TRUE
SYS TEST_EXECUTABLE_PROG TRUE
SYS TEST_STORED_PROCEDURE_PROG TRUE
5 rows selected.
Notice how programs that accept arguments must have the arguments defined before they can be enabled.
Programs can be deleted using theDROP_PROGRAMprocedure:
BEGIN DBMS_SCHEDULER.drop_program (program_name => 'test_plsql_block_prog'); DBMS_SCHEDULER.drop_program (program_name => 'test_stored_procedure_prog'); DBMS_SCHEDULER.drop_program (program_name => 'test_executable_prog'); END; / PL/SQL procedure successfully completed. -- Display the program details. SELECT owner, program_name, enabled FROM dba_scheduler_programs; OWNER PROGRAM_NAME ENABL ------------------------------ ------------------------------ ----- SYS PURGE_LOG_PROG TRUE SYS GATHER_STATS_PROG TRUE 2 rows selected.
Schedules
Schedules optionally define the start time, end time and interval related to a job. Schedules are created using theCREATE_SCHEDULE procedure:
-- Create the schedule.
BEGIN
DBMS_SCHEDULER.create_schedule (
schedule_name => 'test_hourly_schedule',
start_date => SYSTIMESTAMP,
repeat_interval => 'freq=hourly; byminute=0',
end_date => NULL,
comments => 'Repeats hourly, on the hour, for ever.');
END;
/
PL/SQL procedure successfully completed.
-- Display the schedule details.
SELECT owner, schedule_name FROM dba_scheduler_schedules;
OWNER SCHEDULE_NAME
------------------------------ ------------------------------
SYS DAILY_PURGE_SCHEDULE
SYS TEST_HOURLY_SCHEDULE
2 rows selected.
Notice how the interval is defined using the calendaring syntax. A schedule can be dropped using the
DROP_SCHEDULE procedure:
BEGIN DBMS_SCHEDULER.drop_schedule (schedule_name => 'TEST_HOURLY_SCHEDULE'); END; / PL/SQL procedure successfully completed. -- Display the schedule details. SELECT owner, schedule_name FROM dba_scheduler_schedules; OWNER SCHEDULE_NAME ------------------------------ ------------------------------ SYS DAILY_PURGE_SCHEDULE 1 row selected.
Jobs
Jobs are what the scheduler is all about. They can either be made up of predefined parts (programs and schedules) or completely self contained depending on which overload of theCREATE_JOB procedure is used to create them:
-- Create jobs.
BEGIN
-- Job defined entirely by the CREATE JOB procedure.
DBMS_SCHEDULER.create_job (
job_name => 'test_full_job_definition',
job_type => 'PLSQL_BLOCK',
job_action => 'BEGIN DBMS_STATS.gather_schema_stats(''SCOTT''); END;',
start_date => SYSTIMESTAMP,
repeat_interval => 'freq=hourly; byminute=0',
end_date => NULL,
enabled => TRUE,
comments => 'Job defined entirely by the CREATE JOB procedure.');
-- Job defined by an existing program and schedule.
DBMS_SCHEDULER.create_job (
job_name => 'test_prog_sched_job_definition',
program_name => 'test_plsql_block_prog',
schedule_name => 'test_hourly_schedule',
enabled => TRUE,
comments => 'Job defined by an existing program and schedule.');
-- Job defined by existing program and inline schedule.
DBMS_SCHEDULER.create_job (
job_name => 'test_prog_job_definition',
program_name => 'test_plsql_block_prog',
start_date => SYSTIMESTAMP,
repeat_interval => 'freq=hourly; byminute=0',
end_date => NULL,
enabled => TRUE,
comments => 'Job defined by existing program and inline schedule.');
-- Job defined by existing schedule and inline program.
DBMS_SCHEDULER.create_job (
job_name => 'test_sched_job_definition',
schedule_name => 'test_hourly_schedule',
job_type => 'PLSQL_BLOCK',
job_action => 'BEGIN DBMS_STATS.gather_schema_stats(''SCOTT''); END;',
enabled => TRUE,
comments => 'Job defined by existing schedule and inline program.');
END;
/
PL/SQL procedure successfully completed.
-- Display job details.
SELECT owner, job_name, enabled FROM dba_scheduler_jobs;
OWNER JOB_NAME ENABL
------------------------------ ------------------------------ -----
SYS PURGE_LOG TRUE
SYS GATHER_STATS_JOB TRUE
SYS TEST_FULL_JOB_DEFINITION TRUE
SYS TEST_PROG_SCHED_JOB_DEFINITION TRUE
SYS TEST_PROG_JOB_DEFINITION TRUE
SYS TEST_SCHED_JOB_DEFINITION TRUE
6 rows selected.
Jobs are normally run asynchronously under the control of the job coordinator, but they can be controlled manually using the
RUN_JOB and
STOP_JOB procedures:
BEGIN
-- Run job synchronously.
DBMS_SCHEDULER.run_job (job_name => 'test_full_job_definition',
use_current_session => FALSE);
-- Stop jobs.
DBMS_SCHEDULER.stop_job (job_name => 'test_full_job_definition, test_prog_sched_job_definition');
END;
/
Jobs can be deleted using the
DROP_JOB procedure:
BEGIN DBMS_SCHEDULER.drop_job (job_name => 'test_full_job_definition'); DBMS_SCHEDULER.drop_job (job_name => 'test_prog_sched_job_definition'); DBMS_SCHEDULER.drop_job (job_name => 'test_prog_job_definition'); DBMS_SCHEDULER.drop_job (job_name => 'test_sched_job_definition'); END; / PL/SQL procedure successfully completed. -- Display job details. SELECT owner, job_name, enabled FROM dba_scheduler_jobs; OWNER JOB_NAME ENABL ------------------------------ ------------------------------ ----- SYS PURGE_LOG TRUE SYS GATHER_STATS_JOB TRUE 2 rows selected.
Job Classes
Job classes allow grouping of jobs with similar characteristics and resource requierments which eases administration. If theJOB_CLASS parameter of the
CREATE_JOB procedure is undefined the job is assigned to the
DEFAULT_JOB_CLASS. A job class is created using the
CREATE_JOB_CLASS procedure:
-- Display the current resource consumer groups.
SELECT consumer_group FROM dba_rsrc_consumer_groups;
CONSUMER_GROUP
------------------------------
OTHER_GROUPS
DEFAULT_CONSUMER_GROUP
SYS_GROUP
LOW_GROUP
AUTO_TASK_CONSUMER_GROUP
5 rows selected.
-- Create a job class.
BEGIN
DBMS_SCHEDULER.create_job_class (
job_class_name => 'test_job_class',
resource_consumer_group => 'low_group');
END;
/
PL/SQL procedure successfully completed.
-- Display job class details.
SELECT job_class_name, resource_consumer_group FROM dba_scheduler_job_classes;
JOB_CLASS_NAME RESOURCE_CONSUMER_GROUP
------------------------------ ------------------------------
DEFAULT_JOB_CLASS
AUTO_TASKS_JOB_CLASS AUTO_TASK_CONSUMER_GROUP
TEST_JOB_CLASS LOW_GROUP
3 rows selected.
Jobs can be assigned to a job class either during or after creation using the
SET_ATTRIBUTE procedure:
BEGIN
-- Job defined by an existing program and schedule and assigned toa job class.
DBMS_SCHEDULER.create_job (
job_name => 'test_prog_sched_class_job_def',
program_name => 'test_plsql_block_prog',
schedule_name => 'test_hourly_schedule',
job_class => 'test_job_class',
enabled => TRUE,
comments => 'Job defined by an existing program and schedule and assigned toa job class.');
DBMS_SCHEDULER.set_attribute (
name => 'test_prog_sched_job_definition',
attribute => 'job_class',
value => 'test_job_class');
END;
/
PL/SQL procedure successfully completed.
-- Display job details.
SELECT owner, job_name, job_class, enabled FROM dba_scheduler_jobs;
OWNER JOB_NAME JOB_CLASS ENABL
------------------------------ ------------------------------ ------------------------------ -----
SYS PURGE_LOG DEFAULT_JOB_CLASS TRUE
SYS GATHER_STATS_JOB AUTO_TASKS_JOB_CLASS TRUE
SYS TEST_FULL_JOB_DEFINITION DEFAULT_JOB_CLASS TRUE
SYS TEST_PROG_SCHED_JOB_DEFINITION TEST_JOB_CLASS TRUE
SYS TEST_PROG_JOB_DEFINITION DEFAULT_JOB_CLASS TRUE
SYS TEST_SCHED_JOB_DEFINITION DEFAULT_JOB_CLASS TRUE
SYS TEST_PROG_SCHED_CLASS_JOB_DEF TEST_JOB_CLASS TRUE
7 rows selected.
Job classes can be dropped using
DROP_JOB_CLASS procedure:
BEGIN
DBMS_SCHEDULER.drop_job_class (
job_class_name => 'test_job_class',
force => TRUE);
END;
/
PL/SQL procedure successfully completed.
-- Display job class details.
SELECT job_class_name, resource_consumer_group FROM dba_scheduler_job_classes;
JOB_CLASS_NAME RESOURCE_CONSUMER_GROUP
------------------------------ ------------------------------
DEFAULT_JOB_CLASS
AUTO_TASKS_JOB_CLASS AUTO_TASK_CONSUMER_GROUP
2 rows selected.
The force option disables any dependent jobs and sets their job class to the default value. If the job class has no dependents the force option is not necessary.
Windows
Windows provide the link between the scheduler and the resource manager, allowing different resource plans to be activated at different times. Since job classes point to resource consumer groups, and therefore resource plans, this mechanism allows control over the resources allocated to job classes and their jobs during specific time periods.Only one window can be active (open) at any time, with one resource plan assigned to the window. The affect of resource plan switches is instantly visible to running jobs which are assigned to job classes. The interaction between the resource manager and the scheduler is beyond the scope of this document.
A window can be created using the
CREATE_WINDOW procedure with a predefined or an inline schedule:
BEGIN
-- Window with a predefined schedule.
DBMS_SCHEDULER.create_window (
window_name => 'test_window_1',
resource_plan => NULL,
schedule_name => 'test_hourly_schedule',
duration => INTERVAL '60' MINUTE,
window_priority => 'LOW',
comments => 'Window with a predefined schedule.');
-- Window with an inline schedule.
DBMS_SCHEDULER.create_window (
window_name => 'test_window_2',
resource_plan => NULL,
start_date => SYSTIMESTAMP,
repeat_interval => 'freq=hourly; byminute=0',
end_date => NULL,
duration => INTERVAL '60' MINUTE,
window_priority => 'LOW',
comments => 'Window with an inline schedule.');
END;
/
PL/SQL procedure successfully completed.
-- Display window group details.
SELECT window_name, resource_plan, enabled, active
FROM dba_scheduler_windows;
WINDOW_NAME RESOURCE_PLAN ENABL ACTIV
------------------------------ ------------------------------ ----- -----
WEEKNIGHT_WINDOW TRUE FALSE
WEEKEND_WINDOW TRUE FALSE
TEST_WINDOW_1 TRUE FALSE
TEST_WINDOW_2 TRUE FALSE
4 rows selected.
Windows can be opened and closed manually using the
OPEN_WINDOW and
CLOSE_WINDOW procedures:
Windows can be dropped using theBEGIN -- Open window. DBMS_SCHEDULER.open_window ( window_name => 'test_window_2', duration => INTERVAL '1' MINUTE, force => TRUE); END; / PL/SQL procedure successfully completed. -- Display window group details. SELECT window_name, resource_plan, enabled, active FROM dba_scheduler_windows; WINDOW_NAME RESOURCE_PLAN ENABL ACTIV ------------------------------ ------------------------------ ----- ----- WEEKNIGHT_WINDOW TRUE FALSE WEEKEND_WINDOW TRUE FALSE TEST_WINDOW_1 TRUE FALSE TEST_WINDOW_2 TRUE TRUE 4 rows selected. BEGIN -- Close window. DBMS_SCHEDULER.close_window ( window_name => 'test_window_2'); END; / PL/SQL procedure successfully completed. -- Display window group details. SELECT window_name, resource_plan, enabled, active FROM dba_scheduler_windows; WINDOW_NAME RESOURCE_PLAN ENABL ACTIV ------------------------------ ------------------------------ ----- ----- WEEKNIGHT_WINDOW TRUE FALSE WEEKEND_WINDOW TRUE FALSE TEST_WINDOW_1 TRUE FALSE TEST_WINDOW_2 TRUE FALSE 4 rows selected.
DROP_WINDOW procedure:
BEGIN
DBMS_SCHEDULER.drop_window (
window_name => 'test_window_1',
force => TRUE);
DBMS_SCHEDULER.drop_window (
window_name => 'test_window_2',
force => TRUE);
END;
/
PL/SQL procedure successfully completed.
-- Display window group details.
SELECT window_name, resource_plan, enabled, active
FROM dba_scheduler_windows;
WINDOW_NAME RESOURCE_PLAN ENABL ACTIV
------------------------------ ------------------------------ ----- -----
WEEKNIGHT_WINDOW TRUE FALSE
WEEKEND_WINDOW TRUE FALSE
2 rows selected.
Windows Groups
A window group is a collection of related windows. It can be created with 0, 1 or many windows as group members using theCREATE_WINDOW_GROUP procedure:
BEGIN
DBMS_SCHEDULER.create_window_group (
group_name => 'test_window_group',
window_list => 'test_window_1, test_window_2',
comments => 'A test window group');
END;
/
PL/SQL procedure successfully completed.
-- Display window group details.
SELECT window_group_name, enabled, number_of_windowS
FROM dba_scheduler_window_groups;
WINDOW_GROUP_NAME ENABL NUMBER_OF_WINDOWS
------------------------------ ----- -----------------
MAINTENANCE_WINDOW_GROUP TRUE 2
TEST_WINDOW_GROUP TRUE 2
2 rows selected.
Windows can be added and removed from a group using the
ADD_WINDOW_GROUP_MEMBER and
REMOVE_WINDOW_GROUP_MEMBER procedures:
BEGIN
-- Create a new window.
DBMS_SCHEDULER.create_window (
window_name => 'test_window_3',
resource_plan => NULL,
schedule_name => 'test_hourly_schedule',
duration => INTERVAL '60' MINUTE,
window_priority => 'LOW',
comments => 'Window with a predefined schedule.');
DBMS_SCHEDULER.add_window_group_member (
group_name => 'test_window_group',
window_list => 'test_window_3');
END;
/
PL/SQL procedure successfully completed.
-- Display window group members.
SELECT window_group_name, window_name
FROM dba_scheduler_wingroup_members;
WINDOW_GROUP_NAME WINDOW_NAME
------------------------------ ------------------------------
MAINTENANCE_WINDOW_GROUP WEEKNIGHT_WINDOW
MAINTENANCE_WINDOW_GROUP WEEKEND_WINDOW
TEST_WINDOW_GROUP TEST_WINDOW_1
TEST_WINDOW_GROUP TEST_WINDOW_2
TEST_WINDOW_GROUP TEST_WINDOW_3
5 rows selected.
BEGIN
DBMS_SCHEDULER.remove_window_group_member (
group_name => 'test_window_group',
window_list => 'test_window_3');
END;
/
PL/SQL procedure successfully completed.
-- Display window group members.
SELECT window_group_name, window_name
FROM dba_scheduler_wingroup_members;
WINDOW_GROUP_NAME WINDOW_NAME
------------------------------ ------------------------------
MAINTENANCE_WINDOW_GROUP WEEKNIGHT_WINDOW
MAINTENANCE_WINDOW_GROUP WEEKEND_WINDOW
TEST_WINDOW_GROUP TEST_WINDOW_1
TEST_WINDOW_GROUP TEST_WINDOW_2
4 rows selected.
Window groups can be dropped using the
drop_window_group procedure:
BEGIN
DBMS_SCHEDULER.drop_window_group (
group_name => 'test_window_group',
force => TRUE);
END;
/
PL/SQL procedure successfully completed.
-- Display window group details.
SELECT window_group_name, enabled, number_of_windowS
FROM dba_scheduler_window_groups;
WINDOW_GROUP_NAME ENABL NUMBER_OF_WINDOWS
------------------------------ ----- -----------------
MAINTENANCE_WINDOW_GROUP TRUE 2
1 row selected.
The force option must be used if the window group currently has members.
Enable, Disable and Attributes
All applicable scheduler objects can be enabled and disabled using the overloadedENABLE and
DISABLE procedures:
The values for individual attributes of all scheduler objects can be altered using one of theBEGIN -- Enable programs and jobs. DBMS_SCHEDULER.enable (name => 'test_stored_procedure_prog'); DBMS_SCHEDULER.enable (name => 'test_full_job_definition'); -- Disable programs and jobs. DBMS_SCHEDULER.disable (name => 'test_stored_procedure_prog'); DBMS_SCHEDULER.disable (name => 'test_full_job_definition'); END; /
SET_ATTRIBUTE overloads:
BEGIN
DBMS_SCHEDULER.set_attribute (
name => 'hourly_schedule',
attribute => 'repeat_interval',
value => 'freq=hourly; byminute=30');
END;
/
The values can be set to NULL using the
SET_ATTRIBUTE_NULL procedure:
BEGIN
DBMS_SCHEDULER.set_attribute_null (
name => 'hourly_schedule',
attribute => 'repeat_interval');
END;
/