Loading resolved Adaptive Plans in the SQL Plan Management

In my previous post, I have shown that loading Adaptive Plans in the SQL Plan Baseline leads to using the original plan. Well, actually, this is true when you capture them via the OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES parameter.
Thanks to a tweet by Neil Chandler, I’ve realized that it was a good idea to show also the case when the plan is loaded manually.
When the adaptive plan switches to the alternative plan, the plan_hash_value also changes, and can be loaded manually in the baseline with DBMS_SPM.
Let’s reset everything and retry quickly to:
Capture the plan automatically (this will lead to the original plan)
Load the plan manually (I will specify to load the alternative plan, if resolved)
Drop the plan captured automatically
Use the newly accepted baseline
SQL> connect / as sysdba
Connected.

SQL> DECLARE
  2    v_dropped_plans number;
  3  BEGIN
  4    v_dropped_plans := DBMS_SPM.DROP_SQL_PLAN_BASELINE (
  5       sql_handle => 'SQL_6c4c6680810dd01a'
  6  );
  7    DBMS_OUTPUT.PUT_LINE('dropped ' || v_dropped_plans || ' plans');
  8  END;
  9  /

PL/SQL procedure successfully completed.

SQL> select sql_handle, plan_name, sql_text, enabled, accepted, fixed from dba_sql_plan_baselines;

no rows selected

SQL> alter system flush shared_pool;

System altered.

SQL> select sql_id, plan_hash_value, child_number from v$sql where sql_id='1km5kczcgr0fr';

no rows selected

SQL> connect ludo/ludo
Connected.
SQL> ALTER SESSION SET OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES = TRUE;

Session altered.

SELECT /*+ GATHER_PLAN_STATISTICS */
  2         a.data AS tab1_data,
  3         b.data AS tab2_data
  4  FROM   tab1 a
  5         JOIN tab2 b ON b.tab1_id = a.id
  6  WHERE  a.code = 'ONE';

 TAB1_DATA  TAB2_DATA
---------- ----------
...
30 rows selected.

SQL> r
  1  SELECT /*+ GATHER_PLAN_STATISTICS */
  2         a.data AS tab1_data,
  3         b.data AS tab2_data
  4  FROM   tab1 a
  5         JOIN tab2 b ON b.tab1_id = a.id
  6* WHERE  a.code = 'ONE'

 TAB1_DATA  TAB2_DATA
---------- ----------
...
30 rows selected.

SQL> ALTER SESSION SET OPTIMIZER_CAPTURE_SQL_PLAN_BASELINES = FALSE;

Session altered.

SQL> select sql_id, plan_hash_value, child_number from v$sql where sql_id='1km5kczcgr0fr';

SQL_ID                                  PLAN_HASH_VALUE CHILD_NUMBER
--------------------------------------- --------------- ------------
1km5kczcgr0fr                                2672205743            1

SELECT /*+ GATHER_PLAN_STATISTICS */
       a.data AS tab1_data,
  2    3         b.data AS tab2_data
  4  FROM   tab1 a
  5         JOIN tab2 b ON b.tab1_id = a.id
  6  WHERE  a.code = 'ONE';

 TAB1_DATA  TAB2_DATA
---------- ----------
...
30 rows selected.

SQL> select sql_id, plan_hash_value, child_number from v$sql where sql_id='1km5kczcgr0fr';

SQL_ID                                  PLAN_HASH_VALUE CHILD_NUMBER
--------------------------------------- --------------- ------------
1km5kczcgr0fr                                2672205743            1
1km5kczcgr0fr                                2672205743            2

SQL> ALTER SESSION SET OPTIMIZER_USE_SQL_PLAN_BASELINES = FALSE;

Session altered.

SELECT /*+ GATHER_PLAN_STATISTICS */
  2         a.data AS tab1_data,
  3         b.data AS tab2_data
  4  FROM   tab1 a
  5         JOIN tab2 b ON b.tab1_id = a.id
  6  WHERE  a.code = 'ONE';

 TAB1_DATA  TAB2_DATA
---------- ----------
...
30 rows selected.

SQL> select sql_id, plan_hash_value, child_number from v$sql where sql_id='1km5kczcgr0fr';

SQL_ID                                  PLAN_HASH_VALUE CHILD_NUMBER
--------------------------------------- --------------- ------------
1km5kczcgr0fr                                1599395313            0
1km5kczcgr0fr                                2672205743            1
1km5kczcgr0fr                                2672205743            2


SQL> connect / as sysdba
Connected.
SQL> VARIABLE cnt NUMBER
SQL> EXECUTE :cnt := DBMS_SPM.LOAD_PLANS_FROM_CURSOR_CACHE( sql_id => '1km5kczcgr0fr',plan_hash_value => '1599395313');

PL/SQL procedure successfully completed.

SQL> select sql_handle, plan_name, sql_text, enabled, accepted, fixed from dba_sql_plan_baselines;

SQL_HANDLE                PLAN_NAME                           SQL_TEXT                               ENABLED   ACCEPTED  FIXED
------------------------- ----------------------------------- -------------------------------------- --------- --------- ---------
SQL_6c4c6680810dd01a      SQL_PLAN_6sm36h20hvn0u55a25f73      SELECT /*+ GATHER_PLAN_STATISTICS */   YES       YES       NO
                                                                     a.data AS tab1_data,
                                                                     b.data A

SQL_6c4c6680810dd01a      SQL_PLAN_6sm36h20hvn0ud64ac9be      SELECT /*+ GATHER_PLAN_STATISTICS */   YES       YES       NO
                                                                     a.data AS tab1_data,
                                                                     b.data A


SQL> select * from table (DBMS_XPLAN.DISPLAY_SQL_PLAN_BASELINE('SQL_6c4c6680810dd01a', format=>'+adaptive'));

PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------

--------------------------------------------------------------------------------
SQL handle: SQL_6c4c6680810dd01a
SQL text: SELECT /*+ GATHER_PLAN_STATISTICS */        a.data AS tab1_data,
            b.data AS tab2_data FROM   tab1 a        JOIN tab2 b ON b.tab1_id =
          a.id WHERE  a.code = 'ONE'
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
Plan name: SQL_PLAN_6sm36h20hvn0u55a25f73         Plan id: 1436704627
Enabled: YES     Fixed: NO      Accepted: YES     Origin: AUTO-CAPTURE
Plan rows: From dictionary
--------------------------------------------------------------------------------

Plan hash value: 2672205743

---------------------------------------------------------------------------------------------------------
|   Id  | Operation                             | Name          | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------------------------------------
|     0 | SELECT STATEMENT                      |               |    25 |   425 |     3   (0)| 00:00:01 |
|     1 |  NESTED LOOPS                         |               |    25 |   425 |     3   (0)| 00:00:01 |
|     2 |   NESTED LOOPS                        |               |    25 |   425 |     3   (0)| 00:00:01 |
|     3 |    TABLE ACCESS BY INDEX ROWID BATCHED| TAB1          |     1 |    11 |     2   (0)| 00:00:01 |
|  *  4 |     INDEX RANGE SCAN                  | TAB1_CODE     |     1 |       |     1   (0)| 00:00:01 |
|  *  5 |    INDEX RANGE SCAN                   | TAB2_TAB1_FKI |    25 |       |     0   (0)| 00:00:01 |
|     6 |   TABLE ACCESS BY INDEX ROWID         | TAB2          |    25 |   150 |     1   (0)| 00:00:01 |
---------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   4 - access("A"."CODE"='ONE')
   5 - access("B"."TAB1_ID"="A"."ID")

Note
-----
   - this is an adaptive plan (rows marked '-' are inactive)

--------------------------------------------------------------------------------
Plan name: SQL_PLAN_6sm36h20hvn0ud64ac9be         Plan id: 3595225534
Enabled: YES     Fixed: NO      Accepted: YES     Origin: MANUAL-LOAD
Plan rows: From dictionary
--------------------------------------------------------------------------------

Plan hash value: 1599395313

----------------------------------------------------------------------------------------------------
|   Id  | Operation                            | Name      | Rows  | Bytes | Cost (%CPU)| Time     |
----------------------------------------------------------------------------------------------------
|     0 | SELECT STATEMENT                     |           |       |       |     3 (100)|          |
|  *  1 |  HASH JOIN                           |           |    25 |   425 |     3   (0)| 00:00:01 |
|     2 |   TABLE ACCESS BY INDEX ROWID BATCHED| TAB1      |     1 |    11 |     2   (0)| 00:00:01 |
|  *  3 |    INDEX RANGE SCAN                  | TAB1_CODE |     1 |       |     1   (0)| 00:00:01 |
|     4 |   TABLE ACCESS FULL                  | TAB2      |    25 |   150 |     1   (0)| 00:00:01 |
----------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - access("B"."TAB1_ID"="A"."ID")
   3 - access("A"."CODE"='ONE')

Note
-----
   - this is an adaptive plan (rows marked '-' are inactive)

65 rows selected.


SQL> VARIABLE cnt NUMBER
SQL>  EXECUTE :cnt := DBMS_SPM.DROP_SQL_PLAN_BASELINE( SQL_HANDLE => 'SQL_6c4c6680810dd01a',plan_name => 'SQL_PLAN_6sm36h20hvn0u55a25f73');

PL/SQL procedure successfully completed.

SQL> select sql_handle, plan_name, sql_text, enabled, accepted, fixed from dba_sql_plan_baselines;

SQL_HANDLE                PLAN_NAME                           SQL_TEXT                               ENABLED   ACCEPTED  FIXED
------------------------- ----------------------------------- -------------------------------------- --------- --------- ---------
SQL_6c4c6680810dd01a      SQL_PLAN_6sm36h20hvn0ud64ac9be      SELECT /*+ GATHER_PLAN_STATISTICS */   YES       YES       NO
                                                                     a.data AS tab1_data,
                                                                     b.data A

SQL> conn ludo/ludo
Connected.
SELECT /*+ GATHER_PLAN_STATISTICS */
  2         a.data AS tab1_data,
  3         b.data AS tab2_data
  4  FROM   tab1 a
  5         JOIN tab2 b ON b.tab1_id = a.id
  6  WHERE  a.code = 'ONE';

 TAB1_DATA  TAB2_DATA
---------- ----------
...
30 rows selected.

SQL> SELECT * FROM TABLE(DBMS_XPLAN.display_cursor(format => 'allstats last adaptive'));

PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
SQL_ID  1km5kczcgr0fr, child number 2
-------------------------------------
SELECT /*+ GATHER_PLAN_STATISTICS */        a.data AS tab1_data,
b.data AS tab2_data FROM   tab1 a        JOIN tab2 b ON b.tab1_id =
a.id WHERE  a.code = 'ONE'

Plan hash value: 1599395313

---------------------------------------------------------------------------------------------------------------------------------------
| Id  | Operation                            | Name      | Starts | E-Rows | A-Rows |   A-Time   | Buffers |  OMem |  1Mem | Used-Mem |
---------------------------------------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT                     |           |      1 |        |     24 |00:00:00.01 |      71 |       |       |          |
|*  1 |  HASH JOIN                           |           |      1 |     25 |     24 |00:00:00.01 |      71 |  1888K|  1888K| 1921K (0)|
|   2 |   TABLE ACCESS BY INDEX ROWID BATCHED| TAB1      |      1 |      1 |  10001 |00:00:00.01 |      62 |       |       |          |
|*  3 |    INDEX RANGE SCAN                  | TAB1_CODE |      1 |      1 |  10001 |00:00:00.01 |      37 |       |       |          |
|   4 |   TABLE ACCESS FULL                  | TAB2      |      1 |    100 |    100 |00:00:00.01 |       9 |       |       |          |
---------------------------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - access("B"."TAB1_ID"="A"."ID")
   3 - access("A"."CODE"='ONE')

Note
-----
   - SQL plan baseline SQL_PLAN_6sm36h20hvn0ud64ac9be used for this statement


28 rows selected.
To recap:
The capture process will always load the original plan
It is possible to decide to load manually the original one or the alternative one (if resolved)
Using automatic capture is a bad idea
HTH
—
Ludo
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