8/6/2019 Addm Oracle Explained
1/14
Getting to Know
Oracle ADDM
Steve Jun
8/6/2019 Addm Oracle Explained
2/14
Init.ora settings
STATISTICS_LEVEL => {TYPICAL, ALL}
8/6/2019 Addm Oracle Explained
3/14
ADDM Views
DBA_ADVISOR_TASKS
DBA_ADVISOR_LOG DBA_ADVISOR_RECOMMENDATIONS
DBA_ADVISOR_FINDINGS
8/6/2019 Addm Oracle Explained
4/14
DBMS_WORKLOAD_REPOSITORY
CREATE_SNAPSHOT MODIFY_SNAPSHOT_SETTINGS
Retention (minutes)Interval (minutes)TopNSql (number)
8/6/2019 Addm Oracle Explained
5/14
Viewing ADDM data
Views Addmrpt.sql
OEM
8/6/2019 Addm Oracle Explained
6/14
DBMS_ADVISOR.GET_TASK_REPORT TASK_NAME
TYPE LEVEL
SECTION
OWNER
8/6/2019 Addm Oracle Explained
7/14
Viewing ADDM dataSELECT DBMS_ADVISOR.get_task_report(task_name, 'TEXT', 'ALL', 'ALL', 'SYS')
FROM ( SELECT dat.task_nameFROM dba_advisor_tasks dat
, dba_advisor_log dal
WHERE dat.advisor_name = 'ADDM
AND dal.task_id = dat.task_id
AND dat.status = 'COMPLETEDORDER BY dal.execution_end DESC )
WHERE rownum = 1
8/6/2019 Addm Oracle Explained
8/14
Sample OutputFINDING 1: 100% impact (18758 seconds)
--------------------------------------
Hard parses due to an inadequately sized shared pool were consuming
significant database time.
RECOMMENDATION 1: DB Configuration, 100% benefit (11945 seconds)
ACTION: Increase the shared pool size by setting the value of parameter
"shared_pool_size" to 1712 M.
ADDITIONAL INFORMATION:
The value of parameter "shared_pool_size" was "1552 M" during the
analysis period.
SYMPTOMS THAT LED TO THE FINDING:
SYMPTOM: Hard parsing of SQL statements was consuming significant
database time. (4.3% impact [405 seconds])
8/6/2019 Addm Oracle Explained
9/14
Sample OutputFINDING 2: 4.1% impact (385 seconds)
------------------------------------
Session connect and disconnect calls were consuming significant database time.
RECOMMENDATION 1: Application Analysis, 4.1% benefit (385 seconds)
ACTION: Investigate application logic for possible reduction of connect
and disconnect calls. For example, you might use a connection pool
scheme in the middle tier.
8/6/2019 Addm Oracle Explained
10/14
Sample OutputFINDING 3: 100% impact (58925 seconds)
--------------------------------------
The throughput of the I/O subsystem was significantly lower than expected.
RECOMMENDATION 1: Host Configuration, 100% benefit (58925 seconds)
ACTION: Consider increasing the throughput of the I/O subsystem.
Oracle's recommended solution is to stripe all data file using the
SAME methodology. You might also need to increase the number of disks
for better performance. Alternatively, consider using Oracle's
Automatic Storage Management solution.
RATIONALE: During the analysis period, the average data files' I/O
throughput was 4.3 M per second for reads and 22 K per second for
writes. The average response time for single block reads was 1
milliseconds.
8/6/2019 Addm Oracle Explained
11/14
Sample OutputRECOMMENDATION 2: Host Configuration, 11% benefit (716 seconds)
ACTION: The performance of file /oracle/temp/pwcis/temp_03.dbf was
significantly worse than other files. If striping all files using the
SAME methodology is not possible, consider striping this file over
multiple disks.
RELEVANT OBJECT: database file
"/u01/app/oracle/oradata/temp_3.dbf
RATIONALE: The average response time for single block reads for this
file was 91 milliseconds.
8/6/2019 Addm Oracle Explained
12/14
Sample OutputFINDING 4: 8.2% impact (611 seconds)
------------------------------------
SQL statements consuming significant database time were found.
RECOMMENDATION 1: SQL Tuning, 3.3% benefit (247 seconds)
ACTION: Run SQL Tuning Advisor on the SQL statement with SQL_ID
"5uvtb1633rdxt".
RELEVANT OBJECT: SQL statement with SQL_ID 5uvtb1633rdxt and
PLAN_HASH 3487490115
SELECT
FROM c, d
WHERE
RATIONALE: SQL statement with SQL_ID "5uvtb1633rdxt" was executed 79
times and had an average elapsed time of 2.6 seconds.
8/6/2019 Addm Oracle Explained
13/14
Sample OutputRECOMMENDATION 2: SQL Tuning, 3.2% benefit (240 seconds)
ACTION: Run SQL Tuning Advisor on the SQL statement with SQL_ID
"54k7d90u0yzfh".
RELEVANT OBJECT: SQL statement with SQL_ID 54k7d90u0yzfh and
PLAN_HASH 114702621
SELECT
FROM a, b
WHERE
RATIONALE: SQL statement with SQL_ID "54k7d90u0yzfh" was executed 697
times and had an average elapsed time of 0.32 seconds.
8/6/2019 Addm Oracle Explained
14/14
Licensing