ORA-04091 table 正在发生变化

Question

我有以下 2 table：运行s:

+--------+-------------+
| run_id | status      |
+========+=============+
| 1      | active      |
+--------+-------------+
| 2      | new         |
+--------+-------------+

和订单：

+----------+--------+--------------+
| order_id | run_id | order_status |
+==========+========+==============+
| 1        | 1      | finished     |
+----------+--------+--------------+
| 2        | 1      | finished     |
+----------+--------+--------------+
| 3        | 1      | active       |
+----------+--------+--------------+
| 4        | 2      | new          |
+----------+--------+--------------+
| 5        | 2      | active       |
+----------+--------+--------------+
| 6        | 2      | active       |
+----------+--------+--------------+

要求实现以下逻辑：当运行中的所有订单具有相同状态时，应更新运行状态（与其相同订单).

例如，当 order_id = 3 状态设置为 'finished' 时，run_id=1 状态也应设置为 'finished'。与 order_id = 4 相同，当它采用状态 'active' 然后 run_id = 2 should 也设置为 'active'。

负责检查订单状态并相应地更新运行状态的程序：

CREATE OR REPLACE PROCEDURE  check_and_update_run_status  (in_order_id     IN   orders.order_id%TYPE,
                                                           in_run_id       IN   runs.run_id%TYPE,
                                                           in_order_status IN   orders.order_status%TYPE)
AS
   v_update_run VARCHAR2(1) := 'N';
BEGIN
   /*query the table ORDERS and check if all orders in the given in_run_id having the same status as in_order_status: */
  SELECT CASE
           WHEN NOT EXISTS ( SELECT *
                                 FROM ( SELECT order_id,
                                               order_status
                                          FROM orders
                                         WHERE run_id = in_run_id )
                                WHERE order_status <> in_order_status )
             THEN 'Y'
           END
    INTO v_update_run
    FROM dual;

    IF v_update_run THEN
      UPDATE runs
         SET run_status = in_order_status
       WHERE run_id = in_run_id;
    END IF;

END check_and_update_run_status;

我已经创建了触发器

CREATE OR REPLACE TRIGGER trigger1 
AFTER INSERT OR UPDATE OF order_status ON orders FOR EACH ROW 
BEGIN
  check_and_update_run_status( in_order_id  => :new.order_id,
                               in_run_id    => :new.run_id,
                               in_po_status => :new.order_status );
END;

逻辑失败，因为错误：ORA-04091: table ORDERS is mutating, trigger/function may not see it。触发器正在调用一个过程，该过程查询相同的 table 触发器被调用。

解决此类问题的最佳方法是什么？

Answer 1

还有其他方法可以解决 mutating trigger 但我会尝试利用 compound trigger 的功能。话虽如此，我们应该尽可能避免 triggers，在您的情况下，在更新 orders 中的 order status 列期间，在其他程序单元或应用程序代码中的某处调用该过程 table 如我所见，这里的每一行都没有依赖关系，我们需要针对 run_id 而不是 order_id.

进行更新

话虽如此，我对程序做了一些更改，因为在此用例中我们不需要 order_id 参数

CREATE OR REPLACE PROCEDURE check_and_update_run_status
(
   in_run_id       IN runs.run_id%TYPE
  ,in_order_status IN orders.order_status%TYPE
) AS
   v_update_run VARCHAR2(1) := 'N';
BEGIN
   /*query the table ORDERS and check if all orders in the given in_run_id having the same status as in_order_status: */
   SELECT CASE
             WHEN NOT EXISTS (SELECT *
                   FROM   (SELECT order_id
                                 ,order_status
                           FROM   orders
                           WHERE  run_id = in_run_id)
                   WHERE  order_status <> in_order_status) THEN
              'Y' ELSE 'N'
          END
   INTO   v_update_run
   FROM   dual;

   IF v_update_run = 'Y'
   THEN
      UPDATE runs 
         SET status = in_order_status 
       WHERE run_id = in_run_id;
   END IF;

END check_and_update_run_status;
/

并创建 compound trigger 并将过程调用为，

CREATE OR REPLACE TRIGGER trigger1
   FOR INSERT OR UPDATE OF order_status ON orders
   COMPOUND TRIGGER

   --table type to store the status index by run_id value
   TYPE table_a_row_data_t IS TABLE OF orders.order_status%TYPE INDEX BY PLS_INTEGER;

   -- global variable for the compound trigger
   g_row_level_data table_a_row_data_t;

   AFTER EACH ROW IS
   BEGIN
      IF NOT g_row_level_data.exists(:new.run_id)
      THEN
         g_row_level_data(:new.run_id) := :new.order_status;
      END IF;
   END AFTER EACH ROW;

   AFTER STATEMENT IS
   BEGIN
      --loop through all run_id and update the status by calling the procedure
      --here I used collection.first..collection.last as the index is run_id itself  
      FOR runid IN g_row_level_data.first .. g_row_level_data.last
      LOOP
         check_and_update_run_status(in_run_id    => runid
                                    ,in_order_status => g_row_level_data(runid));
      END LOOP;
   END AFTER STATEMENT;
END trigger1;
/

请测试是否符合您的要求。

ORA-04091 table 正在发生变化

ORA-04091 table is Mutating

oracle

triggers

ora-04091

mutating-table