Proactively Maintaining the Database

8Copyright © 2004, Oracle. All rights reserved.

Proactively Maintaining the Database

8-2 Copyright © 2004, Oracle. All rights reserved.

Objectives

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

• Describe the Automatic Workload Repository (AWR)

• Define AWR snapshot baselines

• Subscribe applications to server-generated alerts

• Describe the advisor framework

• Use the Automatic Database Diagnostic Monitor (ADDM)


Oracle Database 10g: Self-Managing Database

Applicationand SQL

management

Storagemanagement

Backup andrecovery

management

Systemresource

management

Spacemanagement

Fix Advise

AlertMonitor

Commonmanageabilityinfrastructure

Automaticmanagement


Automatic Workload Repository

AutomaticWorkload

Repository

Serveralerts

Automatedtasks

Advisorframework

Data warehouseof the database

Automatic collection of important statistics

Direct memoryaccess

Automatic Proactive

Efficient


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

• New 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


Active Session History

SGA

Statistics

V$SESSION

ASH

Recent history

Rolling buffer

AWR snapshots

MMON

MMNL

V$ACTIVE_SESSION_HISTORY


Base Statistics and Metrics

Base Statistic 1

Redo Generation

Metric 1 Metric 2 Redo Generation/Tx

Client 1 Client 2 Client 3 Client 4

MMON

User Commit User Rollback

V$SYSMETRIC, V$SESSMETRIC, V$SERVICEMETRIC, V$METRICNAME

V$FILEMETRIC, V$EVENTMETRIC, V$WAITCLASSMETRIC

Everyminute


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 problemsMMON


Statistic Levels

STATISTICS_LEVEL

BASIC TYPICAL ALL

Recommendeddefault value

Additional statisticsfor manual

SQL diagnostics

Disable all self-tuningcapabilities


AWR Snapshot Baselines

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

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

SYSAUX tablespace

WR schema

Snapshot

Snapshot

Snapshot

Snapshot

7days

Snapshot

60 min

MMON


Database Control and AWR


AWR Reports

SQL> @?/rdbms/admin/awrrpt

Report_type: html

Num_days: 2

Begin_snap: 150

End_snap: 160

Report_name:


Statspack and AWR

Statspackschema

WRschema

Migration

Old application codeusing Statspack

schema


Automatic Routine Administration Tasks

AutomaticWorkload

Repository

Serveralerts

Automatedtasks

Advisorframework

Prepackaged routinemaintenance tasks

Resource usage controlled

Statistics collection task scheduledout-of-the-box

Automatic Proactive

Efficient


Job Scheduler Concepts

Job

Jobclass

Managementwindow

Consumergroup

Windowgroup

Enabled

Disabled

Resourceplan


DBCA and Automated Tasks


Server-Generated Alerts

AutomaticWorkload

Repository

Automatedtasks

Advisorframework

Enabled by default Timely generation

Push model

Automatic Proactive

Efficient

Serveralerts


Server-Generated Alerts: Overview

Oracle Database

(SGA)

Data dictionary

Is there an issue?

There is an issue.

How can I resolve it?

DBA/EM

AWRmetrics


Alert Models: Architecture

Serveralerts

queue.

Oracle database

(SGA)

EMDData

dictionary

Pollstatistics

EMalerts

Server monitors itself.

MMON

AWR

AutomaticPushed

Notification

Serveralerts

Subscribingclients

Thirdparty


Server-Generated Alert Types

MMON

85% Warning

97% Critical Cleared

Cleared

Alert

SnapshotToo Old

ResumableSession

Suspended

Recovery Area Low On

Free Space

Metric-based

Event-based

Threshold(stateful)

alerts

Nonthreshold (stateless)

alerts

DBA_OUTSTANDING_ALERTS DBA_ALERT_HISTORY


Supplied Server-Generated Alerts

ResumableSession

Suspended

SnapshotToo Old

Recovery Area

Low On Free Space

Tablespace

85% Warning97% Critical

TablespaceSpace Usage

Database Control:SYSTEM metrics


Managing Server-Generated Alerts Using Database Control

Set up notification rules (paging, e-mail).

Correct the problem.

Review alert details and advice.

Enable alerts by setting thresholds.

Receive notification.

Verify that the problem is resolved.


Setting Alert Thresholds


Database Control Interface for Alerts


Alerts Notification


Viewing Metric Details


Metric and Alert Views

V$SYSMETRIC_HISTORYV$SYSMETRIC

V$SERVICEMETRICV$METRICNAME

...

DBA_HIST_SYSMETRIC_HISTORY...

DBA_OUTSTANDING_ALERTSDBA_ALERT_HISTORYDBA_THRESHOLDSV$ALERT_TYPES

...

Recent metrics

Metric history

Server alerts


PL/SQL Interface for Threshold Settings

DBMS_SERVER_ALERT

SET_THRESHOLD GET_THRESHOLD

EXECUTE DBMS_SERVER_ALERT.SET_THRESHOLD(DBMS_SERVER_ALERT.CPU_TIME_PER_CALL, DBMS_SERVER_ALERT.OPERATOR_GE, '8000',DBMS_SERVER_ALERT.OPERATOR_GE, '10000', 1,2,'orcl', DBMS_SERVER_ALERT.OBJECT_TYPE_SERVICE,'payroll');

EXECUTE DBMS_SERVER_ALERT.SET_THRESHOLD(6001, NULL, NULL, NULL, NULL, NULL, NULL, 'orcl', DBMS_SERVER_ALERT.OBJECT_TYPE_SERVICE,'payroll');

1

2

Resetting the threshold:


Alert Consumption: Manual Configuration

BEGIN dbms_aqadm.add_subscriber('SYS.ALERT_QUE', sys.aq$_agent('alrt_usr1','', 0)); dbms_aqadm.enable_db_access('alrt_usr1','alrt_usr1'); dbms_aqadm.grant_queue_privilege('DEQUEUE', 'alert_que','alrt_usr1', false);END;

BEGIN dbms_aq.dequeue('SYS.ALERT_QUE', dequeue_options, message_properties, message, message_handle);dbms_output.put_line('Reason: ' || dbms_server_alert.expand_message(userenv('LANGUAGE'),message.message_id, message.reason_argument_1, message.reason_argument_2,message.reason_argument_3,message.reason_argument_4,message.reason_argument_5));END;


Advisor Framework

AutomaticWorkload

Repository

Serveralerts

Automatedtasks

Advisorframework

Uniform interface Fully integrated

Automatic Proactive

Efficient


Advisor Framework: Overview

ADDM

SQL Tuning Advisor

SQL Access Advisor

Memory

Space

PGA Advisor

SGA

Segment Advisor

Undo Advisor

Buffer CacheAdvisor

Library CacheAdvisor

PGA


Using an Advisor for a Typical Tuning Session

1. Create an advisor task.

2. Adjust task parameters.

4. Acceptresults?

5. Implementrecommendations.

Yes

No

3. Perform analysis.


Database Control and Advisors


DBMS_ADVISOR Package

Procedure Description

CREATE_TASK Creates a new task in the repository

DELETE_TASK Deletes a task from the repository

EXECUTE_TASK Initiates execution of the task

INTERRUPT_TASK Suspends a task that is currently executing

GET_TASK_REPORT Provides a text report about recommendations

RESUME_TASK Causes a suspended task to resume

UPDATE_TASK_ATTRIBUTES

Updates task attributes

SET_TASK_PARAMETER Modifies a task parameter

MARK_RECOMMENDATION Marks one or more recommendations as accepted, rejected, or ignored

GET_TASK_SCRIPT Creates a script of all the recommendations that are accepted


Using PL/SQL to Invoke an Advisor

DECLARE taskid NUMBER;BEGIN dbms_advisor.create_task('ADDM',taskid,:tname); dbms_advisor.set_task_parameter(:tname, 'START_SNAPSHOT', 60); dbms_advisor.set_task_parameter(:tname, 'END_SNAPSHOT', 66); dbms_advisor.execute_task(:tname); END;/

SELECT dbms_advisor.get_task_report(:tname)FROM dba_advisor_tasks tWHERE t.task_name = :tname AND t.owner = SYS_CONTEXT('userenv', 'session_user');


Viewing Advisor Information

View Name Description

DBA_ADVISOR_DEFINITIONS Properties of the advisors

DBA_ADVISOR_TASKS Global information about the task

DBA_ADVISOR_LOG Task’s current status information

DBA_ADVISOR_PARAMETERS Task’s parameters

DBA_ADVISOR_COMMANDS Commands associated with actions

DBA_ADVISOR_OBJECTS Object referenced by tasks

DBA_ADVISOR_FINDINGS Findings discovered by the advisor

DBA_ADVISOR_RECOMMENDATIONS Task’s recommendations

DBA_ADVISOR_ACTIONS Actions associated with recommendations

DBA_ADVISOR_RATIONALE Rationales for the recommendations

DBA_ADVISOR_USAGE Usage information for each advisor


Automatic Database Diagnostic Monitor: Overview

• Is a performance-diagnostic engine in the database

• Automatically diagnoses performance problems

• Provides root-cause analysis with recommended solutions

• Identifies areas that have no problems

• Integrates all components and can be used on any database type:– OLTP– Data warehouse– Mixed


ADDM Performance Monitoring

Snapshots

ADDM ADDMresults

In-memorystatistics

AWR

SGA

60 minutes

ADDMresults

EM

MMON


RAC Waits

IO Waits

Concurrency

Buffer Busy

Parse Latches

Buffer Cache latches

Root causesSymptoms

ADDM Methodology

……

…

…Nonproblem areas

Where is timespent?

Goal: Perform the same workload in less time

System Wait


Detecting Top Performance Issues

Excessive logon/logoff

Memory undersizing

Hot blocks and objects w/SQL

RAC service issues

Locks and ITL contention

Checkpointing causes

PL/SQL, Java time

Top SQL

I/O issues

Parsing

Configuration issues

Application usage

Not detectedby Statspack

ADDM identifiestop issues


Database Control and ADDM Findings


Viewing ADDM Analysis Results

1

2

3


Viewing ADDM Recommendations


Creating an 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 with 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 ...


Summary

In this lesson, you should have learned how to:

• Describe the AWR

• Define AWR snapshot baselines

• Subscribe applications to server-generated alerts

• Describe the advisor framework

• Use ADDM


Practice 8 Overview:Using Server-Generated Alerts

This practice covers the following topics:

• Configuring server-generated alerts

• Monitoring server-generated alerts

Documents

Proactively Maintaining the Database