Beware the compound trigger

In 11g, Oracle introduced a new feature in the compound trigger.

Through many years and versions, the solution to the mutating table / ora-04091 problem was often a clumsy combination of packaged global, before statement trigger, after row trigger and after statement trigger.

However, in 11g, the introduction of the compound trigger provided a much more compact solution, where you could declare your global, your statement level logic and any row level code in a single trigger.

Examples from the Oracle documentation:

• Concepts: Compound Triggers
• New Features: Compound Triggers
• PL/SQL Language Reference: Compound Triggers

Trouble is, under certain simple circumstances, they don’t work.

Take this illustration abstracted from a proposed VPD labelling solution on 11.1.0.6.

The illustration is a little artificial because all distractions have been removed but it’s taken from a real world example.

Essentially, three updates via a package cause an ORA-07445 but three direct update statements do not. Take a look:

dominic@DOM11G>prompt ---------- cleanup previous creates
---------- cleanup previous creates
dominic@DOM11G>drop table compound_trigger_test_tab1;

Table dropped.

Elapsed: 00:00:01.02
dominic@DOM11G>drop package compound_trigger_test_pkg;

Package dropped.

Elapsed: 00:00:00.00
dominic@DOM11G>
dominic@DOM11G>prompt ---------- create table
---------- create table
dominic@DOM11G>
dominic@DOM11G>create table compound_trigger_test_tab1
  2  (col1 number
  3  ,col2 number);

Table created.

Elapsed: 00:00:00.00
dominic@DOM11G>
dominic@DOM11G>prompt ---------- insert data
---------- insert data
dominic@DOM11G>
dominic@DOM11G>insert into compound_trigger_test_tab1 values (1,1);

1 row created.

Elapsed: 00:00:00.00
dominic@DOM11G>
dominic@DOM11G>
dominic@DOM11G>prompt ---------- create compound trigger
---------- create compound trigger
dominic@DOM11G>
dominic@DOM11G>CREATE OR REPLACE TRIGGER compound_trigger_test_tri1
  2  FOR INSERT OR UPDATE ON compound_trigger_test_tab1
  3  REFERENCING NEW AS NEW OLD AS OLD
  4  COMPOUND TRIGGER
  5   --
  6   TYPE r_ctt IS RECORD 
  7   (col1    NUMBER
  8   ,col2    NUMBER);
  9   --
 10   TYPE t_ctt IS TABLE OF r_ctt
 11   INDEX BY PLS_INTEGER;
 12   --
 13   vt_ctt t_ctt;
 14   --
 15  BEFORE STATEMENT
 16  IS
 17  BEGIN
 18     --
 19     DBMS_OUTPUT.PUT_LINE('compound_trigger_test_tri1::before statement');
 20     NULL;
 21     --
 22  END BEFORE STATEMENT;
 23  --
 24  BEFORE EACH ROW
 25  IS
 26  BEGIN
 27      --
 28      DBMS_OUTPUT.PUT_LINE('compound_trigger_test_tri1::before row');
 29      NULL;
 30      --
 31  END BEFORE EACH ROW;
 32  --
 33  AFTER EACH ROW
 34  IS
 35  BEGIN
 36     --
 37     DBMS_OUTPUT.PUT_LINE('compound_trigger_test_tri1::after row');
 38     NULL;
 39     --
 40  END AFTER EACH ROW;
 41  --
 42  AFTER STATEMENT
 43  IS
 44    i PLS_INTEGER;
 45  BEGIN
 46     --
 47     DBMS_OUTPUT.PUT_LINE('compound_trigger_test_tri1::after statement');
 48     i := vt_ctt.FIRST;
 49     --
 50     WHILE (i IS NOT NULL)
 51     LOOP
 52         --
 53         NULL;
 54         --
 55         i := vt_ctt.NEXT(i);
 56         --
 57     END LOOP;
 58     --
 59  END AFTER STATEMENT;
 60  --
 61  END compound_trigger_test_tri1;
 62  /

Trigger created.

Elapsed: 00:00:00.00
dominic@DOM11G>
dominic@DOM11G>show errors
No errors.
dominic@DOM11G>
dominic@DOM11G>
dominic@DOM11G>prompt ---------- create package header
---------- create package header
dominic@DOM11G>
dominic@DOM11G>CREATE OR REPLACE PACKAGE compound_trigger_test_pkg
  2  AS
  3    --
  4    PROCEDURE p_update_tab1 (
  5      i_col1                     in     compound_trigger_test_tab1.col1%TYPE
  6    );
  7    --
  8  END;
  9  /

Package created.

Elapsed: 00:00:00.00
dominic@DOM11G>
dominic@DOM11G>
dominic@DOM11G>prompt ---------- create package body
---------- create package body
dominic@DOM11G>
dominic@DOM11G>CREATE OR REPLACE PACKAGE BODY compound_trigger_test_pkg
  2  AS
  3    --
  4    PROCEDURE p_update_tab1 (
  5      i_col1                     in     compound_trigger_test_tab1.col1%TYPE
  6    )
  7    AS
  8    BEGIN
  9       --
 10       DBMS_OUTPUT.PUT_LINE('compound_trigger_test_pkg.p_update_tab1');
 11       UPDATE compound_trigger_test_tab1
 12       SET    col2 = col2
 13       WHERE  col1 = i_col1;
 14       --
 15    END p_update_tab1;
 16  END;
 17  /

Package body created.

Elapsed: 00:00:00.00
dominic@DOM11G>
dominic@DOM11G>
dominic@DOM11G>prompt ---------- run update via package test 1 - should be ok
---------- run update via package test 1 - should be ok
dominic@DOM11G>exec compound_trigger_test_pkg.p_update_tab1(1);

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.00
dominic@DOM11G>
dominic@DOM11G>prompt ---------- run update via package 2 - should be ok
---------- run update via package 2 - should be ok
dominic@DOM11G>exec compound_trigger_test_pkg.p_update_tab1(2);

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.00
dominic@DOM11G>
dominic@DOM11G>prompt ---------- run update via package 3 - should go bang
---------- run update via package 3 - should go bang
dominic@DOM11G>exec compound_trigger_test_pkg.p_update_tab1(3);
BEGIN compound_trigger_test_pkg.p_update_tab1(3); END;

*
ERROR at line 1:
ORA-03113: end-of-file on communication channel


Elapsed: 00:00:00.05
dominic@DOM11G>conn dominic@dom11g
Enter password: *******
Connected.
dominic@DOM11G>UPDATE compound_trigger_test_tab1
  2  SET    col2 = col2
  3  WHERE  col1 = 1;

1 row updated.

Elapsed: 00:00:00.00
dominic@DOM11G>
dominic@DOM11G>UPDATE compound_trigger_test_tab1
  2  SET    col2 = col2
  3  WHERE  col1 = 2;

0 rows updated.

Elapsed: 00:00:00.00
dominic@DOM11G>
dominic@DOM11G>UPDATE compound_trigger_test_tab1
  2  SET    col2 = col2
  3  WHERE  col1 = 3;

0 rows updated.

Elapsed: 00:00:00.00
dominic@DOM11G>

Alert log and trace file reveal the cause to be an ORA-07445:

Exception [type: SIGSEGV, Address not mapped to object] [ADDR:0x448] [PC:0x1B6A3B8, kkxtexe()+988]
Errors in file /app/oracle/diag/rdbms/dom11g/DOM11G/trace/dom11G_ora_4860.trc  (incident=845912):
ORA-07445: exception encountered: core dump [kkxtexe()+988] [SIGSEGV] [ADDR:0x448] [PC:0x1B6A3B8] [Address not mapped to object] []
ORA-21779: duration not active

So, for the moment, I would not go near them.
I’ve got an SR raised (it’s all I seem to doing these days is find bugs in 11.1.0.6 (more on the incompatibility between VPD and Materialized Views another time) and 11.1.0.7)
It’s back to multiple row and statement level triggers.

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