如何在openGauss 2.1.0中使用Job?

Job类似Unix中的crontab,有定时执行的功能，可以在指定的时间点或每天的某个时间点等自行执行任务。在各类系统使用运行过程中，经常会遇到需要定时完成的任务，比如定时更新数据，定时统计数据生成报表等等，这些工作都可以使用Job来完成。在openGauss 2.1.0中，提供了以下接口来实现管理Job。
接口描述

接口定义和使用示例

• PKG_SERVICE.JOB_CANCEL
  存储过程CANCEL删除指定的定时任务。

PKG_SERVICE.JOB_CANCEL函数原型为：

PKG_SERVICE.JOB_CANCEL( job IN INTEGER);

示例：

CALL PKG_SERVICE.JOB_CANCEL(101);

• PKG_SERVICE.JOB_FINISH
  存储过程FINISH禁用或者启用定时任务。

PKG_SERVICE.JOB_FINISH函数原型为：

PKG_SERVICE.JOB_FINISH( id IN INTEGER, broken IN BOOLEAN, next_time IN TIMESTAMP DEFAULT sysdate);

• PKG_SERVICE.JOB_SUBMIT
  存储过程JOB_SUBMIT提交一个系统提供的定时任务。

PKG_SERVICE.JOB_SUBMIT函数原型为：

PKG_SERVICE.JOB_SUBMIT( id IN BIGINT DEFAULT, content IN TEXT, next_date IN TIMESTAMP DEFAULT sysdate, interval_time IN TEXT DEFAULT ‘null’, job OUT INTEGER);

当创建一个定时任务（JOB）时，系统默认将当前数据库和用户名与当前创建的定时任务绑定起来。该接口函数可以通过call或select调用，如果通过select调用，可以不填写出参。如果在存储过程中，则需要通过perform调用该接口函数。如果提交的sql语句任务使用到非public的schema，应该指定表或者函数的schema，或者在sql语句前添加set current_schema = xxx;语句。

示例：

SELECT PKG_SERVICE.JOB_SUBMIT(NULL, 'call pro_xxx();', 
to_date('20180101','yyyymmdd'),'sysdate+1'); SELECT PKG_SERVICE.JOB_SUBMIT(NULL, 
'call pro_xxx();', to_date('20180101','yyyymmdd'),'sysdate+1.0/24'); CALL
PKG_SERVICE.JOB_SUBMIT(NULL, 'INSERT INTO T_JOB VALUES(1); call pro_1(); call 
pro_2();', add_months(to_date('201701','yyyymm'),1), 'date_trunc(''day'',SYSDATE)
+ 1 +(8*60+30.0)/(24*60)' ,:jobid); SELECT PKG_SERVICE.JOB_SUBMIT (101,
'insert_msg_statistic1;', sysdate, 'sysdate+3.0/24');

• PKG_SERVICE.JOB_UPDATE
  存储过程UPDATE修改定时任务的属性，包括任务内容、下次执行时间、执行间隔。

PKG_SERVICE.JOB_UPDATE函数原型为：

PKG_SERVICE.JOB_UPDATE( id IN BIGINT, next_time IN TIMESTAMP, interval_time IN TEXT, content IN TEXT);

示例：

CALL PKG_SERVICE.JOB_UPDATE(101,'call userproc();', sysdate, 'sysdate + 
1.0/1440'); CALL PKG_SERVICE.JOB_UPDATE(101, 'insert into tbl_a 
values(sysdate);', sysdate, 'sysdate + 1.0/1440');

• PKG_SERVICE.SUBMIT_ON_NODES
  存储过程SUBMIT_ON_NODES创建一个所有CN/DN上的定时任务，仅sysadmin有此权限。

PKG_SERVICE.SUBMIT_ON_NODES函数原型为：

PKG_SERVICE.SUBMIT_ON_NODES( node_name IN TEXT, database IN TEXT what IN TEXT, next_date IN TIMESTAMP DEFAULT sysdate, job_interval IN TEXT DEFAULT 'null', job OUT INTEGER)

示例：

select pkg_service.submit_on_nodes('ALL_NODE', 'postgres', 'select capture_view_to_json(''dbe_perf.statement'', 0);', sysdate, 'interval ''60 second''');
select pkg_service.submit_on_nodes('CCN', 'postgres', 'select capture_view_to_json(''dbe_perf.statement'', 0);', sysdate, 'interval ''60 second''');

• PKG_SERVICE.ISUBMIT_ON_NODES
  ISUBMIT_ON_NODES与SUBMIT_ON_NODES语法功能相同，但其第一个参数是入参，即指定的作业号，SUBMIT最后一个参数是出参，表示系统自动生成的作业号。仅sysadmin有此权限。

JOB的使用示例

• 创建测试表
  

  gaussdb@postgres> create table t_job (value TIMESTAMP);
  CREATE TABLE
  
  gaussdb@postgres> insert into t_job values(sysdate);
  INSERT 0 1
  
  gaussdb@postgres> select * from t_job;
  +---------------------+
  | value               |
  |---------------------|
  | 2021-10-09 04:36:20 |
  +---------------------+
  SELECT 1​

   

   

• 创建任务，每一分钟插入一条记录
  

  gaussdb@postgres> select pkg_service.job_submit(null, 'insert into t_job values(sysdate);',sysdate,'sysdate + 1/1440');
  +--------------+
  | job_submit   |
  |--------------|
  | 15566        |
  +--------------+
  SELECT 1​

   

• 检查Job运行结果
  

  gaussdb@postgres> select * from t_job;
  +---------------------+
  | value               |
  |---------------------|
  | 2021-10-09 04:36:20 |
  | 2021-10-09 04:40:54 |
  | 2021-10-09 04:41:54 |
  | 2021-10-09 04:42:54 |
  +---------------------+
  SELECT 4​

   

   

• 从系统视图中检查Job运行情况
  

  gaussdb@postgres> select job_id,dbname,start_date,next_run_date,interval,failure_count from pg_job;
  +----------+----------+----------------------------+---------------------+------------------+-----------------+
  | job_id   | dbname   | start_date                 | next_run_date       | interval         | failure_count   |
  |----------+----------+----------------------------+---------------------+------------------+-----------------|
  | 15566    | postgres | 2021-10-09 04:40:54.072363 | 2021-10-09 04:56:54 | sysdate + 1/1440 | 0               |
  +----------+----------+----------------------------+---------------------+------------------+-----------------+
  SELECT 1
  Time: 0.089s
  gaussdb@postgres> select * from pg_catalog.pg_job_proc pjp where job_id=15566;
  +----------+------------------------------------+
  | job_id   | what                               |
  |----------+------------------------------------|
  | 15566    | insert into t_job values(sysdate); |
  +----------+------------------------------------+
  SELECT 1
  Time: 0.089s​

   

   

• 修改为2分钟执行一次
  

  gaussdb@postgres> select pkg_service.job_update(15566,null,'sysdate + 2/1440',null);
  +--------------+
  | job_update   |
  |--------------|
  |              |
  +--------------+
  SELECT 1​

• 检查修改情况和运行结果
  

  [gaussdb@postgres> select job_id,interval from pg_job where job_id=15566;
  +----------+------------------+
  | job_id   | interval         |
  |----------+------------------|
  | 15566    | sysdate + 2/1440 |
  +----------+------------------+
  SELECT 1](<gaussdb@postgres%3E select * from t_job;
  +---------------------+
  | value               |
  |---------------------|
  | 2021-10-09 04:36:20 |
  | 2021-10-09 04:40:54 |
  | 2021-10-09 04:41:54 |
  | 2021-10-09 04:42:54 |
  | 2021-10-09 04:43:54 |
  | 2021-10-09 04:44:54 |
  | 2021-10-09 04:45:54 |
  | 2021-10-09 04:46:54 |
  | 2021-10-09 04:47:54 |
  | 2021-10-09 04:48:54 |
  | 2021-10-09 04:49:54 |
  | 2021-10-09 04:50:54 |
  | 2021-10-09 04:51:54 |
  | 2021-10-09 04:52:54 |
  | 2021-10-09 04:53:54 |
  | 2021-10-09 04:54:54 |
  | 2021-10-09 04:55:54 |
  | 2021-10-09 04:56:54 |
  | 2021-10-09 04:57:54 |
  | 2021-10-09 04:58:54 |
  | 2021-10-09 04:59:54 |
  | 2021-10-09 05:00:55 |
  | 2021-10-09 05:01:56 | <---
  | 2021-10-09 05:03:57 | <--- 开始间隔2分钟
  +---------------------+
  SELECT 24
  Time: 0.088s
  gaussdb@postgres> select job_id,interval,next_run_date from pg_job where job_id=15566;
  +----------+------------------+---------------------+
  | job_id   | interval         | next_run_date       |
  |----------+------------------+---------------------|
  | 15566    | sysdate + 2/1440 | 2021-10-09 05:05:57 |
  +----------+------------------+---------------------+
  SELECT 1
  Time: 0.078s>​

   

   

• 禁用和启用任务
  禁用和启用都是同样的函数pkg_service.job_finish，传入不同的参数表示是禁用还是启用。

gaussdb@postgres> select pkg_service.job_finish(15566,true,null);
+--------------+
| job_finish   |
|--------------|
|              |
+--------------+
SELECT 1
Time: 0.089s
gaussdb@postgres> select job_id,next_run_date,job_status from pg_job where job_id=15566;
+----------+---------------------+--------------+
| job_id   | next_run_date       | job_status   |
|----------+---------------------+--------------|
| 15566    | 4000-01-01 00:00:00 | d            |
+----------+---------------------+--------------+
SELECT 1
Time: 0.075s
gaussdb@postgres> select pkg_service.job_finish(15566,false,null);
+--------------+
| job_finish   |
|--------------|
|              |
+--------------+
SELECT 1
Time: 0.091s
gaussdb@postgres> select job_id,next_run_date,job_status from pg_job where job_id=15566;
+----------+---------------------+--------------+
| job_id   | next_run_date       | job_status   |
|----------+---------------------+--------------|
| 15566    | 4000-01-01 00:00:00 | s            |
+----------+---------------------+--------------+
SELECT 1
Time: 0.080s

可以看到如果重新启用任务的时候，没有指定下次运行时间，那么下次运行时间会始终保持在4000年，意味着仍然不会启动，所以如果禁用任务之后再重新启动，需要手动显式指定下次运行时间。

gaussdb@postgres> select pkg_service.job_finish(15566,false,sysdate);
+--------------+
| job_finish   |
|--------------|
|              |
+--------------+
SELECT 1
Time: 0.088s
gaussdb@postgres> select job_id,next_run_date,job_status from pg_job where job_id=15566;
+----------+---------------------+--------------+
| job_id   | next_run_date       | job_status   |
|----------+---------------------+--------------|
| 15566    | 2021-10-09 05:16:22 | s            |
+----------+---------------------+--------------+
SELECT 1
Time: 0.086s

• 删除任务

gaussdb@postgres> select pkg_service.job_cancel(15566);
+--------------+
| job_cancel   |
|--------------|
|              |
+--------------+
SELECT 1
Time: 0.082s
gaussdb@postgres> select job_id,next_run_date,job_status from pg_job where job_id=15566;
+----------+-----------------+--------------+
| job_id   | next_run_date   | job_status   |
|----------+-----------------+--------------|
+----------+-----------------+--------------+
SELECT 0
Time: 0.086s
gaussdb@postgres> select * from pg_catalog.pg_job_proc pjp where job_id=15566;
+----------+--------+
| job_id   | what   |
|----------+--------|
+----------+--------+
SELECT 0
Time: 0.087s

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