Oracle 11gR2: Can I use DBMS_PARALLEL_EXECUTE to run my custom PL/SQL code?

Question

I prepared some fiddle:

CREATE TABLE t_process
    ("process_number" int, "process_status" varchar2(12))
;

INSERT ALL 
    INTO t_process ("process_number", "process_status")
         VALUES (1, 'PROCESSING')
    INTO t_process ("process_number", "process_status")
         VALUES (2, 'PROCESSING')
    INTO t_process ("process_number", "process_status")
         VALUES (3, 'TO_BE_KILLED')
    INTO t_process ("process_number", "process_status")
         VALUES (4, 'PROCESSING')
    INTO t_process ("process_number", "process_status")
         VALUES (5, 'PROCESSING')
    INTO t_process ("process_number", "process_status")
         VALUES (6, 'TO_BE_KILLED')
    INTO t_process ("process_number", "process_status")
         VALUES (7, 'TO_BE_KILLED')
    INTO t_process ("process_number", "process_status")
         VALUES (8, 'WAITING')
    INTO t_process ("process_number", "process_status")
         VALUES (9, 'KILLED')
SELECT * FROM dual
;

This is my processing procedure:

CREATE OR REPLACE PROCEDURE MY_PROCEDURE(IN_ID IN NUMBER) IS
BEGIN
  UPDATE T_PROCESS SET process_status = 'KILLING' WHERE process_number = IN_ID;
  COMMIT;
  -- DO SOME STUFF
  UPDATE T_PROCESS SET process_status = 'KILLED' WHERE process_number = IN_ID;
  COMMIT;
END MY_PROCEDURE;

Now I want to use DBMS_PARALLEL_EXECUTE to run this custom SQL:

DECLARE
  id1 number = :id1;
  id2 number = :id2;
BEGIN
  MY_PROCEDURE(id1);
END;

So, my question is:

Can I use DBMS_PARALLEL_EXECUTE to execute above SQL statement?

Because I only found UPDATE examples. Maybe CREATE_CHUNKS_BY_SQL to select only TO_BE_KILLED and then RUN_TASK with above statement?

Answer 1

YES, You can very well do that 11g onwards. I am surprised why it was not suggested here.

You can execute a procedure inside run_task like begin MY_PROCEDURE( :start_id, :end_id ); end;

You may need to modify procedure to accept two parameters :start_id, :end_id

Here is the sample code (based on ‘create_chunks_by_rowid’).

DECLARE
  l_task     VARCHAR2(30) := 'parallel_processing';
  l_sql_stmt VARCHAR2(32767);
  l_try      NUMBER;
  l_status   NUMBER;
BEGIN
  DBMS_PARALLEL_EXECUTE.create_task (task_name => l_task);

  DBMS_PARALLEL_EXECUTE.create_chunks_by_rowid(task_name   => l_task,
                                               table_owner => 'SCHEMANAME',
                                               table_name  => 'T_PROCESS',
                                               by_row      => TRUE,
                                               chunk_size  => 10000);

  l_sql_stmt := 'begin MY_PROCEDURE( :start_id, :end_id ); end;';

  DBMS_PARALLEL_EXECUTE.run_task(task_name      => l_task,
                                 sql_stmt       => l_sql_stmt,
                                 language_flag  => DBMS_SQL.NATIVE,
                                 parallel_level => 10);

  -- If there is error, RESUME it for at most 2 times.
  l_try := 0;
  l_status := DBMS_PARALLEL_EXECUTE.task_status(l_task);
  WHILE(l_try < 2 and l_status != DBMS_PARALLEL_EXECUTE.FINISHED) 
  Loop
    l_try := l_try + 1;
    DBMS_PARALLEL_EXECUTE.resume_task(l_task);
    l_status := DBMS_PARALLEL_EXECUTE.task_status(l_task);
  END LOOP;

  DBMS_PARALLEL_EXECUTE.drop_task(l_task);
END;
/

You can create chunks by following means as well based upon your situation / comfort.

CREATE_CHUNKS_BY_NUMBER_COL -- If you want to update by 'process_number'

CREATE_CHUNKS_BY_SQL -- If you think BY_SQL is going to give you a very smaller set of chunks to be processed. Beware of the fact that each chunk will be able to process just 1 row per chunk (start_id and end_id will same for each chunk) in this approach.