DBMS_并行_执行。仅当任务存在时才删除它-Oracle 11g

您可以查询该表 USER_PARALLEL_EXECUTE_TASKS 或 DBA_PARALLEL_EXECUTE_TASKS 检查任务是否存在。

SQL> select TASK_NAME,STATUS FROM user_parallel_execute_tasks WHERE TASK_NAME = 'xyz';
TASK_NAME                           |STATUS
--------------------------------------------
xyz                                 |CREATED

因此,在您的过程中添加类似的内容。

SELECT COUNT(*)
INTO ct
FROM user_parallel_execute_tasks
WHERE task_name = p_task_name;

IF ct > 0 THEN
  DBMS_PARALLEL_EXECUTE.DROP_TASK(p_task_name);
END  IF;

如果删除不存在的任务 TASK_NOT_FOUND 引发异常

SQL> 
SQL>  exec DBMS_PARALLEL_EXECUTE.DROP_TASK('NOTEXIST');

Error starting at line : 3 in command -
BEGIN DBMS_PARALLEL_EXECUTE.DROP_TASK('NOTEXIST'); END;
Error report -
ORA-29498: task not found
ORA-06512: at "SYS.DBMS_PARALLEL_EXECUTE_INTERNAL", line 219
ORA-06512: at "SYS.DBMS_PARALLEL_EXECUTE_INTERNAL", line 316
ORA-06512: at "SYS.DBMS_PARALLEL_EXECUTE", line 100
ORA-06512: at line 1
29498. 00000 -  "task not found" 
*Cause:    The task did not exist.
*Action:   Use an existing task.

因此,您可以放弃任务,然后像这样捕获异常

SQL> begin 
  2     DBMS_PARALLEL_EXECUTE.DROP_TASK('NOTEXIST');
  3  exception
  4     WHEN DBMS_PARALLEL_EXECUTE.TASK_NOT_FOUND THEN NULL;
  5  END;

PL/SQL procedure successfully completed.