A couple of years ago I set myself a best practice goal of preferring SPM baselines over SQL-Profiles. I must recognize that I failed to achieve this goal. Fortunately as of Oracle 12cR2 it becomes possible to load SPM baselined plans directly from AWR tables. This is why I am now unexcused to do not operate the switch.
Let’s see first how we can load SPM plans using AWR historical tables
Setting the Scenes
create table t_acs(n1 number, n2 number);
BEGIN
for j in 1..1200150 loop
if j = 1 then
insert into t_acs values (j, 1);
elsif j>1 and j<=101 then
insert into t_acs values(j, 100);
elsif j>101 and j<=1101 then
insert into t_acs values (j, 1000);
elsif j>10001 and j<= 110001 then
insert into t_acs values(j,10000);
else
insert into t_acs values(j, 1000000); end if;
end loop;
commit;
END;
/
create index t_acs_i1 on t_acs(n2);
BEGIN
dbms_stats.gather_table_stats
(user
,'t_acs'
,method_opt => 'for all columns size skewonly'
,cascade => true
,estimate_percent => dbms_stats.auto_sample_size );
END;
/
exec dbms_workload_repository.create_snapshot;
var ln2 number;
exec :ln2 := 100
select count(1) from t_acs where n2 = :ln2;
exec :ln2 := 1e6
select count(1) from t_acs where n2 = :ln2;
select count(1) from t_acs where n2 = :ln2;
exec :ln2 := 100
select count(1) from t_acs where n2 = :ln2;
exec dbms_workload_repository.create_snapshot;
If you copy and past the above SQL code into a SQL PLUS session and issue the following select you should find that you have already two bind aware cursors:
select
sql_id
,child_number
,is_bind_sensitive
,is_bind_aware
,executions
from
v$sql
where
sql_id = 'f2pmwazy1rnfd'
and is_shareable = 'Y';
SQL_ID CHILD_NUMBER I I EXECUTIONS
------------- ------------ - - ----------
f2pmwazy1rnfd 1 Y Y 1
f2pmwazy1rnfd 2 Y Y 1
The bind awareness property of the above cursor has nothing to do with the bottom line of this article. It is here just because I will use the same model in my next article where this time this particular property becomes necessary.
If I would have decided to create a SQL profile over the above cursor I would have then opted for Carlos Sierra coe_xfr_sql_profile.sql script as shown below:
SQL> @coe_xfr_sql_profile.sql
Parameter 1:
SQL_ID (required)
Enter value for 1: f2pmwazy1rnfd
PLAN_HASH_VALUE AVG_ET_SECS
--------------- -----------
535703726 ,054
1882749816 ,085
Parameter 2:
PLAN_HASH_VALUE (required)
Enter value for 2: 1882749816
Values passed:
~~~~~~~~~~~~~
SQL_ID : "f2pmwazy1rnfd"
PLAN_HASH_VALUE: "1882749816"
Execute coe_xfr_sql_profile_f2pmwazy1rnfd_1882749816.sql
on TARGET system in order to create a custom SQL Profile
with plan 1882749816 linked to adjusted sql_text.
SQL>@coe_xfr_sql_profile_f2pmwazy1rnfd_1882749816.sql
... manual custom SQL Profile has been created
COE_XFR_SQL_PROFILE_f2pmwazy1rnfd_1882749816 completed
As such the next time I will run this query it will use the fixed SQL Profile as shown below:
SQL> select count(1) from t_acs where n2 = :ln2;
SQL> select * from table(dbms_xplan.display_cursor);
Plan hash value: 1882749816
------------------------------------------------------
| Id | Operation | Name | Rows | Bytes |
------------------------------------------------------
| 0 | SELECT STATEMENT | | | |
| 1 | SORT AGGREGATE | | 1 | 3 |
|* 2 | INDEX RANGE SCAN| T_ACS_I1 | 100 | 300 |
------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - access("N2"=:LN2)
Note
-----
- SQL profile coe_f2pmwazy1rnfd_1882749816 used for this statement
However until the arrival of 12cR2 it was impossible to load a SPM plan baseline for the above cursor using corresponding AWR historical execution plan. Hopefully it is now possible. This is below how to capture SPM plan from AWR:
SQL>@LoadSPMfromAwr.sql
Listing latest AWR snapshots ...
SNAP_ID END_INTERVAL_TIME
---------- ---------------------------
14 08/03/17 13:20:09,251000000
15 08/03/17 14:00:13,233000000
16 08/03/17 15:07:46,465000000
17 09/03/17 01:13:41,092000000
18 09/03/17 12:11:26,748000000
19 10/03/17 01:07:36,836000000
20 10/03/17 10:08:54,214000000
21 10/03/17 12:35:26,590000000
22 11/03/17 01:04:40,947000000
23 12/03/17 12:41:35,578000000
24 12/03/17 15:03:55,730000000
25 13/03/17 02:21:01,517000000
26 13/03/17 12:53:22,204000000
27 13/03/17 15:43:46,522000000
28 14/03/17 13:13:07,716000000
29 15/03/17 12:55:54,089000000
30 16/03/17 12:59:39,201000000
31 17/03/17 02:09:14,047000000
32 17/03/17 10:38:33,520000000
33 17/03/17 12:50:59,072000000
20 rows selected.
Enter begin snapshot id: 14
Enter end snapshot id: 27
Enter value for sql_filter: sql_text like ''select count(1) from t_acs%''
SQL> select
plan_name ,origin
from dba_sql_plan_baselines;
PLAN_NAME ORIGIN
---------------------------------------- ---------------------
SQL_PLAN_fn4mhg52jx5z125348c47 MANUAL-LOAD-FROM-AWR
SQL_PLAN_fn4mhg52jx5z13069e6f9 MANUAL-LOAD-FROM-AWR
SQL> select count(1) from t_acs where n2 = :ln2;
SQL> select * from table(dbms_xplan.display_cursor);
SQL_ID f2pmwazy1rnfd, child number 1
-------------------------------------
select count(1) from t_acs where n2 = :ln2
Plan hash value: 1882749816
------------------------------------------------------
| Id | Operation | Name | Rows | Bytes |
------------------------------------------------------
| 0 | SELECT STATEMENT | | | |
| 1 | SORT AGGREGATE | | 1 | 3 |
|* 2 | INDEX RANGE SCAN| T_ACS_I1 | 100 | 300 |
-------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - access("N2"=:LN2)
Note
-----
- SQL profile coe_f2pmwazy1rnfd_1882749816 used for this statement
- SQL plan baseline SQL_PLAN_fn4mhg52jx5z125348c47 used for this statement
You have to choose the snap interval that includes historical details of your sql_id
Here’s below the content of the script I used to capture SPM plan from AWR
PROMPT Listing latest AWR snapshots ...
SELECT snap_id, end_interval_time
FROM dba_hist_snapshot
WHERE end_interval_time > SYSDATE - 30
ORDER BY end_interval_time;
ACCEPT bsnapid NUMBER PROMPT "Enter begin snapshot id: "
ACCEPT esnapid NUMBER PROMPT "Enter end snapshot id: "
SET TERMOUT OFF PAGESIZE 0 HEADING OFF LINESIZE 1000 TRIMSPOOL ON TRIMOUT ON TAB OFF
declare
rs pls_integer;
begin
rs := dbms_spm.load_plans_from_awr('&bsnapid', '&esnapid', '&sql_filter');
end;
/
SET TERMOUT ON PAGESIZE 5000 HEADING ON
