6 Copyright © 2006, Oracle. All rights reserved. Using Automatic Workload Repository.

6Copyright © 2006, Oracle. All rights reserved.

Using Automatic Workload Repository

6-2 Copyright © 2006, Oracle. All rights reserved.

Objectives

After completing this lesson, you should be able to do the following:

• Create and manage Automatic Workload Repository (AWR) snapshots

• Generate AWR reports

• Create snapshot sets and compare periods

• Generate ADDM reports

• Generate ASH reports


Automatic Workload Repository: Overview

SGA

V$ DBA_*

ADDM Self-tuningcomponent

Self-tuningcomponent

…Internal clients

External clientsEM SQL*Plus …

Efficientin-memorystatisticscollection

AWRsnapshotsMMON


Automatic Workload Repository Data

• Base statistics:– SQL and optimizer

statistics– OS statistics– Wait classes– Time statistics

• Metrics

• Active Session History

• Advisor results

• Snapshot statistics

• Database feature usage

V$SYSSTATV$SQL

V$SEGMENT_STATISTICSV$SYS_TIME_MODEL

V$SYSMETRIC_HISTORYV$SYSTEM_WAIT_CLASS

V$OSSTATV$ACTIVE_SESSION_HISTORY

DBA_ADVISOR_*DBA_HIST_*

DBA_FEATURE_*DBA_HIGH_WATER_MARK_*

DBA_TAB_STATS_HISTORY


Workload Repository

SYSAUX

SGA

In-memorystatistics

6:00 a.m.7:00 a.m.

8:00 a.m.

Snapshot 1Snapshot 2Snapshot 3

Snapshot 49:00 a.m.

9:30 a.m.

ADDM finds top problems.MMON


AWR Snapshot Sets

DBMS_WORKLOAD_REPOSITORY.CREATE_BASELINE ( - start_snap_id IN NUMBER , end_snap_id IN NUMBER , baseline_name IN VARCHAR2);

Relevant periodin the past


AWR Snapshot Purging Policy

SYSAUX tablespace

sys schema

Snapshot

Snapshot

Snapshot

Snapshot

7days

Snapshot

MMON

Every night

60 min


AWR Snapshot Settings

DBMS_WORKLOAD_REPOSITORY.MODIFY_SNAPSHOT_SETTINGS ( - retention IN NUMBER DEFAULT NULL, interval IN NUMBER DEFAULT NULL, topnsql IN NUMBER DEFAULT NULL);


Database Control and AWR


Generating AWR Reports in EM


Generating AWR Reports in SQL*Plus


Snapshot Sets and Period Comparisons


Compare Periods: Benefits

DBA

≠

DBA

≠


Compare Periods: General


Compare Periods: Report


AWR Data

Advisorresults

AWR

SQLstatistics

Basestatistics

Metrics ASH


DBMS_WORKLOAD_REPOSITORY Package

Procedure to modify the snapshot settings

MODIFY_SNAPSHOT_SETTINGS

Procedure to drop a single AWR baseline

DROP_BASELINE

Procedure to create a single AWR baseline

CREATE_BASELINE

Procedure to drop a range of snapshotsDROP_SNAPSHOT_RANGE

Procedure to create a manual snapshot immediately

CREATE_SNAPSHOT

DescriptionProcedure Name


ADDM Performance Monitoring

Snapshots

ADDM

In-memorystatistics

AWR

SGA

60 minutes

ADDM results

MMON


ADDM and Database Time

Wide area network

Application server

Local area network

Oracle database

User sendsa request.

User getsa response.

User 1

User 2

User n

Connect Execute Fetch Fetch Fetch Execute

Database time Wall-clock time


DBTime-graph and ADDM Methodology

Userconnect

Root node

SQLoptimization

SQLexecution

Undersizedbuffer cache

I/Ocapacity

Databaselocks

Insufficient I/Obandwidth

CPUcapacity

Dimension 1 Dimension 2

Symptoms

Root causes


Top Performance Issues Detected

Excessive logon/logoff

Memory undersizing

Hot blocks and objects w/SQL

RAC service issues

Locks and ITL contention

Checkpointing causes

PL/SQL, Java time

Streams, AQ, and RMAN

Top SQL

I/O issues

Parsing

Configuration issues

Application usage

Not detectedby Statspack

ADDM identifies

top issues.


Database Control and ADDM Findings


ADDM Analysis Results

1

2

3


ADDM Recommendations


Database Control and ADDM Task


Changing ADDM Attributes

1. Ensure that STATISTICS_LEVEL is set to TYPICAL or ALL.

2. ADDM analysis of I/O performance depends on the expected speed of the I/O subsystem:a. Measure your I/O subsystem speed.

b. Set the expected speed.

SQL> exec DBMS_ADVISOR.SET_DEFAULT_TASK_PARAMETER(- 'ADDM', 'DBIO_EXPECTED', 8000);

SELECT parameter_value, is_defaultFROM dba_advisor_def_parametersWHERE advisor_name = 'ADDM' AND parameter_name = 'DBIO_EXPECTED';


Retrieving ADDM Reports by Using SQL

SELECT dbms_advisor.GET_TASK_REPORT(task_name)FROM dba_advisor_tasksWHERE task_id = ( SELECT max(t.task_id) FROM dba_advisor_tasks t, dba_advisor_log l WHERE t.task_id = l.task_id AND t.advisor_name = 'ADDM' AND l.status = 'COMPLETED');

SQL> @?/rdbms/admin/addmrpt…Enter value for begin_snap: 8Enter value for end_snap: 10…Enter value for report_name: Generating the ADDM report for this analysis ...


Active Session History: Overview

• Stores the history of database time

• Samples session activity in the system including:– SQL identifier of a SQL statement – Object number, file number, and block number – Wait event identifier and parameters – Session identifier and session serial number – Module and action name – Client identifier of the session – Service hash identifier– Blocking session

• Is always on for first fault analysis

• No need to replay the workload


Active Session History: Mechanics

SGA

Statistics

V$SESSION

ASH

Recent history

Rollingbuffer

Workload repository

1sec

1sec

1sec

Every60 minutes

MMON

MMNL

When 66% full

V$ACTIVE_SESSION_HISTORY

WRH$_ACTIVE_SESSION_HISTORY (partitioned)

No useof SQL

Direct pathinserts

DBA_HIST_ACTIVE_SESSION_HISTORY

1 outof 10

Viewers gounlatched.


ASH Sampling: Example

Session1

Wait I/OWait LockWait BlockWait I/OWait I/OWait LockWait I/O

Wait Block

…

…

Sess1 Wait I/OSess1 Wait I/O

Sess1 Wait Block

Session2active

Session3active

Sessionnactive

…

Active Inactivesessions

1sec

1sec ASH

…


Time


Accessing ASH Data

• Dump to trace file

• V$ACTIVE_SESSION_HISTORY• DBA_HIST_ACTIVE_SESS_HISTORY• ASH report

• EM Diagnostic Pack performance pages

• ADDM


Dump ASH to File

The generated file contains ASH samples for the last number of minutes specified:

SQL> oradebug setmypid

SQL> oradebug dump ashdump 10

<<<ACTIVE SESSION HISTORY - PROCESS TRACE DUMP HEADER BEGIN>>>

DBID, INSTANCE_NUMBER, SAMPLE_ID, SAMPLE_TIME, SESSION_ID, SESSION_SERIAL#, USER_ID, SQL_ID, SQL_CHILD_NUMBER, SQL_PLAN_HASH_VALUE, SERVICE_HASH, SESSION_TYPE, SQL_OPCODE, BLOCKING_SESSION, BLOCKING_SESSION_SERIAL# QC_SESSION_ID, QC_INSTANCE_ID, XID, CURRENT_OBJ#, CURRENT_FILE#, CURRENT_BLOCK#, EVENT_ID, SEQ#, P1, P2, P3, WAIT_TIME, TIME_WAITED, FORCE_MATCHING_SIGNATURE, PROGRAM, MODULE, ACTION, CLIENT_ID

<<<ACTIVE SESSION HISTORY - PROCESS TRACE DUMP HEADER END>>>

<<<ACTIVE SESSION HISTORY - PROCESS TRACE DUMP BEGIN>>>

1090770270,1,1317127,"08-26-2005 01:11:40.505471000", 162, 1, 0, "", 0, 0, 165959219, 2, 0, 4294967295, 0,0,0,,5129,1,11242,86156091,1664,0,0,0,0,64620,0,"oracle@edrsr14p1 (CJQ0)","","","",1090770270,1,1317116,"08-26-2005 01:11:29.505471000", 142,20,24, "0hbv80w9ypy0n",0,3304045827, 3427055676, 1,3,4294967291, 0,0,0,,8751, 3,2486, 1421975091,24975,1413697536,1,0,620,0,17258348159868772889,"emagent@edrsr14p1 (TNS V1-V3)","emagent@edrsr14p1 (TNS V1-V3)","",""

…

<<<ACTIVE SESSION HISTORY - PROCESS TRACE DUMP END>>>


Sifting the ASHes

• GROUP BY and COUNT– Proxy for nonidle elapsed time– Proportions of actual time spent

• Can analyze any time slice

• Example: Returns most active SQL in the past minute

SELECT sql_id, count(*), round(count(*)/sum(count(*)) over (), 2) pctload

FROM v$active_session_history

WHERE sample_time > sysdate -1/24/60 and

session_type <> 'BACKGROUND'

GROUP BY sql_id

ORDER BY count(*) desc;


Generating ASH Reports


ASH Report Script

SQL> define dbid = '';

SQL> define inst_num = '';

SQL> define report_type = 'html';

SQL> define begin_time = '09:00';

SQL> define duration = 480;

SQL> define report_name = '/tmp/sql_ashrpt.txt';

SQL> define slot_width = '';

SQL> define target_session_id = '';

SQL> define target_sql_id = 'abcdefghij123';

SQL> define target_wait_class = '';

SQL> define target_service_hash = '';

SQL> define target_module_name = '';

SQL> define target_action_name = '';

SQL> define target_client_id = '';

SQL> @?/rdbms/admin/ashrpti


ASH Report: General Section


DBA_HIST_ACTIVE_SESSION_HISTORY


ASH Report Structure


ASH Report: Activity Over Time


Practice Overview: Use AWR-Based Tools

This practice covers the following topics:

• Generate an AWR report

• Create a preserved set on snapshots

• Generate an ADDM report

• Generate an ASH Report


Summary

In this lesson, you should have learned how to:

• Create and manage AWR snapshots

• Generate AWR reports

• Create snapshot sets and compare periods

• Generate ADDM reports

• Generate ASH reports

6 Copyright © 2006, Oracle. All rights reserved. Using Automatic Workload Repository.

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Transcript of 6 Copyright © 2006, Oracle. All rights reserved. Using Automatic Workload Repository.