Oracle DBMS_PARALLEL_EXECUTE 用于合并 stmt

Question

我已经使用 Oracle DBMS pkg 进行并行执行，并且工作正常。

现在我正在尝试使用来运行一个简单的 MERGE stmt。它给了我各种各样的错误。我尝试了相同的 pkg create_chunks_by_rowid 和 create_chunks_by_number_col 所有这些错误。

我的问题是它（DBMS_PARALLEL_EXECUTE pkg）可以处理合并stmt还是我做错了什么？ 如有任何帮助，我们将不胜感激。

顺便说一句，合并 sql stmt 在 sql 中运行时运行良好。

下面给出的是我尝试使用的合并 stmt，并从 pkg 中获取错误。

CREATE TABLE test_tab (
  id          NUMBER,
  description VARCHAR2(50),
  num_col     NUMBER,
  session_id  NUMBER,
  CONSTRAINT test_tab_pk PRIMARY KEY (id)
);

INSERT /*+ APPEND */ INTO test_tab
SELECT level,
       'Description for ' || level,
       CASE
         WHEN MOD(level, 5) = 0 THEN 10
         WHEN MOD(level, 3) = 0 THEN 20
         ELSE 30
       END,
       SYS_CONTEXT(''USERENV'',''SESSIONID'')
FROM   dual
CONNECT BY level <= 1000000;
COMMIT;

create table test_tab2 as select * from test_tab;

delete from test_tab where rownum<500001;
commit;

exec DBMS_PARALLEL_EXECUTE.drop_task (task_name => 'test_task');
exec DBMS_PARALLEL_EXECUTE.create_task (task_name => 'test_task');

SELECT DBMS_PARALLEL_EXECUTE.generate_task_name
FROM   dual;

set serverout on;
DECLARE
l_stmt  varchar2(32767);
BEGIN
  l_stmt := 'MERGE into test_tab2 b
            using test_tab a
            on (a.id=b.id)
            when matched then 
                update set b.session_id = a.session_id
            when not matched then
                insert (id,description,num_col,session_id)
                values(a.id,a.description,a.num_col,a.session_id)';

  DBMS_PARALLEL_EXECUTE.create_chunks_by_sql(task_name => 'test_task',
                                             sql_stmt  => l_stmt,
                                             by_rowid  => FALSE);
                                            
END;
/

Error report -
ORA-01007: variable not in select list
ORA-06512: at "SYS.DBMS_PARALLEL_EXECUTE", line 373
ORA-06512: at "SYS.DBMS_SQL", line 1641
ORA-06512: at "SYS.DBMS_PARALLEL_EXECUTE", line 324
ORA-06512: at line 13
01007. 00000 -  "variable not in select list"
*Cause:    
*Action:

Answer 1

不要使用那个包，它太麻烦了。只需启用并行 dml 并提示查询即可：

BEGIN
    EXECUTE IMMEDIATE 'alter session enable parallel dml';

    MERGE /*+ parallel(16) append */ into test_tab2 b
            using test_tab a
            on (a.id=b.id)
            when matched then 
                update set b.session_id = a.session_id
            when not matched then
                insert (id,description,num_col,session_id)
                values(a.id,a.description,a.num_col,a.session_id);
    COMMIT;
END;