AWR report analysis

[jonengo]

Hello All

I have the following problem:

When I create an awr report within two snapshots say 24139 and 24140 , I get from the part of "SQL ordered by Elapsed Time" the following information:

SQL ordered by Elapsed Time DB/Inst: DEVC/DEVC Snaps: 24139-24140
-> Resources reported for PL/SQL code includes the resources used by all SQL
statements called by the code.
-> % Total DB Time is the Elapsed Time of the SQL statement divided
into the Total Database Time multiplied by 100


OUTPUT
------------------------------------------------------------------
Elapsed CPU Elap per % Total
Time (s) Time (s) Executions Exec (s) DB Time SQL Id
---------- ---------- ------------ ---------- ------- -------------
39 39 2 19.7 14.4 dccxnr2d9b3xd

So far so good.
The problem is that I want to retrieve the same information from the DBMS_SQLTUNE.SELECT_WORKLOAD_REPOSITORY for the same snapshot interval I get:


exec dbms_sqltune.create_sqlset ('MYSQLSET2');

DECLARE
cur DBMS_SQLTUNE.SQLSET_CURSOR;
BEGIN

OPEN cur FOR
SELECT VALUE(P)
FROM table(
DBMS_SQLTUNE.SELECT_WORKLOAD_REPOSITORY(24139,24140)) P;

DBMS_SQLTUNE.LOAD_SQLSET(sqlset_name => 'MYSQLSET2',
populate_cursor => cur);
END;
/


When I query the information I realize that nothing matchs with the AWR report (for example , the same sql_id as different number of executions)

SQL> SELECT sql_id,elapsed_time,cpu_time,executions, round(((elapsed_time/1000000)/decode(executions, 0, 1, executions))
2 'MYSQLSET2', -- sqlset_name
3 NULL, -- basic_filter
4 NULL, -- object_filter
5 NULL, -- ranking_measure1
6 NULL, -- ranking_measure2
7 NULL, -- ranking_measure3
8 NULL, -- result_percentage
9 NULL) -- result_limit
10 )
11 where sql_id ='dccxnr2d9b3xd'
12 order by 2 desc;

SQL_ID ELAPSED_TIME CPU_TIME EXECUTIONS RATIO
------------- ------------ ---------- ---------- ----------
dccxnr2d9b3xd 63592931 62241266 3 21.2


Does anyone have an ideia why the values are different while query the same repository?
I need to retrieve the correct information and I don't know which of the sources I should rely.
Thank you in advance for any help

[LKBrwn_DBA]

Data in the repository are SNAPSHOTS. The correct value would be computed as snapshot (n) minus snapshot (n-1).

[jonengo]

LKBrwn,
Thank you very much for your answer.
I completely agree with you.
The problem is that, as far as I understand, the procedure DBMS_SQLTUNE.SELECT_WORKLOAD_REPOSITORY(24139,24140)) is computing the values in the same way as the AWR report. Otherwise, why does it takes as arguments two snapshots?

[jonengo]

I will try to formulate again the question:

I have the following problem:

I need to retrieve information about query performance (not as a report but as a query output to be used in OS scripts)
The problem is that I really don't know where to rely upon the information that I retrieve from two different sources. Let me explain:

When I create an AWR report within two snapshots say 24139 and 24140 , I get from the part of "SQL ordered by Elapsed Time" the following information:

SQL ordered by Elapsed Time DB/Inst: DEVC/DEVC Snaps: 24139-24140
-> Resources reported for PL/SQL code includes the resources used by all SQL
statements called by the code.
-> % Total DB Time is the Elapsed Time of the SQL statement divided
into the Total Database Time multiplied by 100

OUTPUT (for sql_id = dccxnr2d9b3xd)

Elapsed
Time(s)
39

CPU
Time(s)
39

Executions
2

Elap per %
Exec (s)
19.7

Total
DB Time
14.4

SQL Id
dccxnr2d9b3xd

So far so good.
Querying the I get the conclusion that AWR report in fact is computing the delta values of the snapshots ( snap(n) - snap(n-1) ), for example for executions number:

select snap_id, executions_total from dba_hist_sqlstat
where sql_id ='dccxnr2d9b3xd';

SNAP_ID EXECUTIONS_TOTAL
---------- ----------------
24139 1
24140 3

The problem is that when I want to retrieve the same information from the DBMS_SQLTUNE.SELECT_WORKLOAD_REPOSITORY whithin the same snapshot interval as follow:

DECLARE
cur DBMS_SQLTUNE.SQLSET_CURSOR;
BEGIN

OPEN cur FOR
SELECT VALUE(P)
FROM table(
DBMS_SQLTUNE.SELECT_WORKLOAD_REPOSITORY(24139,24140)) P;

DBMS_SQLTUNE.LOAD_SQLSET(sqlset_name => 'MYSQLSET2',
populate_cursor => cur);
END;
/

SELECT sql_id,elapsed_time,cpu_time,executions, round(((elapsed_time/1000000)/decode(executions, 0, 1, executions)),1) as ratio FROM TABLE (DBMS_SQLTUNE.select_sqlset (
'MYSQLSET2', -- sqlset_name
NULL, -- basic_filter
NULL, -- object_filter
NULL, -- ranking_measure1
NULL, -- ranking_measure2
NULL, -- ranking_measure3
NULL, -- result_percentage
NULL) -- result_limit
)
where sql_id ='dccxnr2d9b3xd'
order by 2 desc;

The result is the follow:

SQL_ID /ELAPSED_TIME /CPU_TIME /EXECUTIONS /RATIO
dccxnr2d9b3xd / 63592931 / 62241266 / 3 / 21.2

When I query the previous sqlset_name I get 3 as the number of executions for sql_id ='dccxnr2d9b3xd' withing the same snapshot interval.
Due this, I wondering myself if this function (DBMS_SQLTUNE.SELECT_WORKLOAD_REPOSITORY(snap_id1, spnap_id2)) ought compute the values in the same delta way as the AWR report.


Can anyone please give me an explanation/interpretation about the difference in both results?