addm oracle explained

8/6/2019 Addm Oracle Explained

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Getting to Know

Oracle ADDM

Steve Jun


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Init.ora settings

STATISTICS_LEVEL => {TYPICAL, ALL}


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ADDM Views

DBA_ADVISOR_TASKS

DBA_ADVISOR_LOG DBA_ADVISOR_RECOMMENDATIONS

DBA_ADVISOR_FINDINGS


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DBMS_WORKLOAD_REPOSITORY

CREATE_SNAPSHOT MODIFY_SNAPSHOT_SETTINGS

Retention (minutes)Interval (minutes)TopNSql (number)


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Viewing ADDM data

Views Addmrpt.sql

OEM


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DBMS_ADVISOR.GET_TASK_REPORT TASK_NAME

TYPE LEVEL

SECTION

OWNER


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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


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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])


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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.


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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.


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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.


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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.


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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.


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