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Maximizing Database Performance: Performance Tuning with DB

Time

Kurt Engeleiter, John Beresniewicz, Cecilia Gervasio

Oracle America

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The following is intended to outline our general

product direction. It is intended for information

purposes only, and may not be incorporated into any

contract. It is not a commitment to deliver any

material, code, or functionality, and should not be

relied upon in making purchasing decisions.

The development, release, and timing of any

features or functionality described for Oracle‟s

products remains at the sole discretion of Oracle.

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Agenda

• NEWS: DB Time is not news

• DB Time Fundamentals

• DB Time Method for Performance Tuning

• DB Time Based Tools

– ADDM

– Enterprise Manager

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NEWS: DB Time is Not News

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DB Time is Pervasive, Familiar, Evolutionary

• DB Time is the fundamental measure of Oracle

performance

– Arrived at progressively but designed-in from 10g

• You are likely using DB Time methods already

– AWR and ASH reports

– Enterprise Manager

• DB Time is performance analysis science matured

– Wait event analysis, YAPP and tracing are all its ancestors

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DB Time on the Database Home Page

• Host CPU

• Is host CPU-bound? Is this DB responsible?

• Active Sessions

• DB Time accumulation by CPU, User I/O, Wait

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DB Time on the Performance Page

• Area under curve is equal to DB time

• Wait class breakdown indicates solution space

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DB Time on the Top Activity Page

DB Time

• Plots DB Time from ASH data

• Shows top DB Time consumers by SQL and Session

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DB Time in AWR Report

• Time Model measures and

accumulates DB Time through

session instrumentation

• DB Time and DB CPU most

important

• Also shows DB Time expended

in various sub-operations

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DB Time in AWR Report

• If you tune by Wait

Events you are tuning by

DB Time

• Top 5 Timed Events in

the AWR report shows

CPU time and non-idle

waits for foregrounds

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DB Time in the Grid Control DB Loadmap

• Maps DB Time across the enterprise

• Cell size proportional to DB Time

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DB Time Fundamentals

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Why Do We Care About Time?

• Human time is critical to the enterprise

• Systems performance affects business goals

– Human time + technology resource time

• “Time is money”

• Performance improvement means doing things faster

Performance is always and only about time

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DB Time Defined

• Total time in database calls by foreground sessions

• Includes CPU time, IO time and non-idle wait time

• DB Time is not called response time on purpose

• Common currency for Oracle performance analysis

Database time is total time spent by user processes either actively working or actively

waiting in a database call.

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Active Session = Session currently spending time in a database call

Database Time (DB Time) =Total time session spends in all database calls

Average Activity of the Session (% Activity) = Ratio of time active to total wall clock time= Sum(Active Time) / Elapsed Time

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TIME

= time spent in database

Session-level Concepts

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= time spent in database

Multiple Sessions

TIME

User 1

User 2

User 3

User n

DB Time = Sum of DB Time over all sessions

Avg. Active Sessions = Sum of Avg. Activity over all sessions

= Sum(DB Time) / Elapsed Time

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TIME

User 3User 2User 1

User n

t0 t1

1

2

3

4

Active Sessions over time

Visualizing DB Time

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Enterprise Manager Performance Page

• Active Sessions by wait class over time

• Colored area is the amount of DB Time

DB Time on User I/O is always blue

DB Time on CPU is always green

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DB Time and

System Performance

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System Load and DB Time

• More users

More database calls

DB Time increases

• Larger transactions

More SQLs per call

DB Time increases

DB time increases as system load increases.

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System Performance and DB Time

• I/O performance degrades

I/O wait time increases

DB Time increases

• Application performance degrades

Longer elapsed time per SQL

DB Time increases

DB time increases as performance degrades.

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Host Performance and DB Time

• Host is CPU bound

Foregrounds accumulate active run-queue time

Wait event times are artificially inflated

DB Time increases

Tune for CPU before waits when CPU constrained

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CPU Run-Queue and DB Time

Db file sequential read

Run-queue

On CPU Db file sequential read

Run-queue

On CPU

DB time is inflated when host is CPU-bound

User 1

Actual wait time Actual wait time

Recorded wait time Recorded wait time

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The DB Time Method for

Performance Tuning

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The DB Time Method: Short Course

Determine where database

time is spent, and reduce it!

or

just ask ADDM

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The DB Time Method: Process

1. Identify performance issue

2. Scope the issue

3. Set goals

4. Data capture

5. Investigate DB time distribution

– Identify largest potential improvement

6. Modify system to tune for largest gain

7. Evaluate against goals

Performance tuning by removing excess DB time

AWR handles this

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Identify and Scope the Problem

• Big spike = big problem!

• Container (host) or database issue?

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Investigate DB Time Distribution

• Identify excess DB time

– Look for large skews in time that may represent inefficiencies

• System scope:

– Resource limits – is problem outside the DB?

– Resource contention (latches)

• Application scope:

– Service, module, action

– SQLID, rowsource

– Resource contention (enqueues)

• Session scope:

– Long-running SQL

– Resource contention (holding enqueues in uncommitted txns)

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Investigate DB Time distribution

• Which wait classes are dominant?

• “Top” lists show skew in key dimensions (SQL, session, file, etc.)

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Identify Time-saving Modifications

• System scope:

– Initialization parameter changes

– Add resources or capacity

• Application scope:

– SQL Tuning Advisor: SQL profiles

– Real-time SQL Monitoring

– Access Advisor: Physical schema layout

– Re-write SQL

• Session scope:

– Kill session for immediate contention relief

– Application design changes often long-term solution

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Critical Success Factors

• Match solution scope to problem scope

– Don‟t tweak optimizer parameters before tuning SQL

• Address root causes, not symptoms

• Proceed iteratively one fix at a time

– Concurrent fixes should be orthogonal

• Measure and validate results at each successive step

• Stop when goals are met

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Advantages of the DB Time Method

• Tunes exactly what affects users: – Time wasted in database

• Data capture not necessary:– „Always on‟ instrumentation framework (AWR, ASH)

– No requirement to reproduce problem (unlike tracing)

• Superior coverage of all scope levels– Works for concurrency problems such as locking

– Tight integration with kernel-engineered tools

• Maturation and extension of well-proven methodologies

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DB Time Based Tools:

ADDM

Enterprise Manager

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Tools for Applying DB Time Method

Two use-cases, one method:

1. Tuning steady-state performance

– Improve overall workload throughput or response time

– Best practice: use ADDM

2. Diagnosing transient performance problems

– Confirm and investigate reported performance issues

– Best practice: use EM real-time screens

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Example: Using ADDM

• Users complain about bad performance

• AWR report indicates some unusual issues on system

• What to do?

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What does the Internet advise?

• Let‟s search on „enq: HW contention‟

• 9,000 hits and LOTS of discussion

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Example: Following the links

• Many hits are other people asking the same question – what do I

do about this wait event?

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Solution: ADDM in Enterprise Manager

• Performance Page shows a spike of unusual activity

• Click on the ADDM analysis icon

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Solution: Using ADDM

• ADDM performance findings are DB Time based

• Ranked by impact = percent of DB Time affected

• Click on the issue with the highest impact

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Solution: Using ADDM

• ADDM recommendations describe solutions for findings

• EM presents „implement‟ actions where possible

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Best Practice: Enterprise Manager Real-time Interface

• Transient (sub-hour) or immediate time scope

– Requires interactivity of UI

• „Click on the big stuff‟

– Data visualizations display skew directly

• Takes some expertise to separate symptoms from

root causes

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Click on the Big Stuff – Follow the DB Time

• Spike in DB Time signals possible performance issue

• Click through to Top Activity for more details

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Follow the DB Time – Top Activity Drilldown

• Top Activity Page confirms problem and shows highly skewed DB

Time by SQL ID. Click on top SQL ID for further details.

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Click on the Big Stuff – Follow the DB Time

• SQL Details confirms this SQL produced the spike in DB Time and

shows parallel execution. Click on „SQL Monitoring‟ to see DB

Time by execution plan steps.

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Follow the DB Time – SQL Execution Details

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DB Time Method Summary

• DB time is the fundamental performance metric

• The method allows DB time analysis at many scopes

– Proper scoping of problems and solutions is critical to success

• DB time based diagnosis removes value judgments

– Scientific method, not sorcerer‟s magic

Performance improvement means doing the same work in less DB Time

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Oracle Enterprise Manager 11g

Resource CenterAccess Videos, Webcasts, White Papers, and More

Oracle.com/enterprisemanager11g

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Additional Oracle Enterprise Manager Sessions

Wednesday, Sept. 22 Location

• 10:00 a.m. - Manage the Manager: Diagnosing and Tuning

Oracle Enterprise Manager• Moscone S Rm 102

• 11:30 a.m. - Maximizing Database Performance: Performance

Tuning with DB Time• Moscone S Rm 104

• 11:30 a.m. - Make Upgrades Uneventful Using Oracle

Enterprise Manager and My Oracle Support• Moscone S Rm 310

• 12:30pm – Extracting Real Value from Your Data with Apache

Hadoop• Hilton Hotel, Plaza B

• 1:00 p.m.- Reducing the Risk of SOA Transactions• Marriott Marquis, Salon

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• 1:00 p.m. - SQL Tuning Roundtable with Oracle Gurus • Moscone S Rm102

• 4:45 p.m.- Strategies for Monitoring Large Datacenters with

Oracle Enterprise Manager• Moscone S Rm102

• 4:45 p.m.- Oracle SOA Management Best Practices, Tips, and

Techniques

• Moscone W L3, Rm

3018

• 4:45 p.m.- Oracle E-Business Suite Technology: Vision,

Release Overview, Product Roadmap


3002 / 3004

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Thursday, Sept. 23 Location

• 9:00 a.m. - Oracle WebLogic Server Management for Oracle

DBAs

• Marriott Marquis,

Salon 9

• 9:00 a.m. - Enabling Database as a Service Through Agile Self-

Service Provisioning

• Moscone S. Room

102

• 9:00 a.m. - Reduce TCO with Oracle Application Management

Pack for Oracle E-Business Suite


2024

• 10:30 a.m. - Best Practices for Managing Your PeopleSoft

Applications

• Marriott Hotel, Golden

Gate A

• 10:30 a.m. - Oracle Enterprise Manager Grid Control

Deployment Best Practices

• Moscone S. Room

102

• 10:30 a.m. - Managing Sun SPARC Servers with Oracle

Enterprise Manager Ops Center

• Moscone S. Room

252

• 10:30 a.m. - Heterogeneous Data Masking: Oracle, SQL Server,

and DB2 Database Best Practices

• Moscone S. Room

306

• 12:00 p.m. - Scalable Enterprise Data Processing for the Cloud

with Oracle Grid Engine

• Moscone S. Room

310

• 12:00 p.m. - Spot Problems Before Your Users Call: User

Experience Monitoring for Oracle Apps

• Marriott Hotel, Golden

Gate A

• 12:00 p.m. - Reduce Problem Resolution Time with Oracle

Database 11g Diagnostic Framework

• Moscone S. Room

102

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Thursday, Sept. 23 Location

• 1:30 p.m. - Patching Enterprisewide Databases: Automation

Techniques and Real-World Insights

• Moscone S. Room

310

• 1:30 p.m. - Managing User Experience: Lessons from eBay• Marriott Hotel, Golden

Gate A

• 1:30 p.m. - Deep Java Diagnostics and Performance Tuning:

Expert Tips and Techniques


Salon 9

• 1:30 p.m. - Oracle Enterprise Manager Configuration

Management Unleashed: Top 10 Expert Tips


Salon 6

• 1:30 p.m. - Oracle Enterprise Manager Security Best Practices• Moscone S. Room

102

• 3:00 p.m - The X-Files: Managing the Oracle Exadata and

Highly Available Oracle Databases

• Moscone S. Room

102

• 3:00 p.m. - Monitoring and Diagnosing Oracle RAC

Performance with Oracle Enterprise Manager

• Moscone S. Room

310

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Oracle Enterprise Manager Hands On LabsMonday September 20, 2010

3:30 p.m. - 4:30 p.m. Database Performance Diagnostics and Tuning Marriott Hotel,Salon 12/13, YB Level

5:00 p.m. - 6:00 p.m. Provisioning, Patch Automation, and Configuration Management Pack Marriott Hotel,Salon 12/13, YB Level

5:00 p.m. - 6:00 p.m. Oracle Application Mgmt. Pack for Oracle E-Business Suite: Monitor/Clone Marriott Marquis, Nob Hill

Tuesday September 21, 2010

11:00 a.m.-12:00 p.m. Using Oracle Application Change Management Pack for Oracle E-Business Suite Marriott Marquis, Nob Hill

12:30 p.m.-1:30 p.m. Database and Application Testing Marriott Hotel, Salon 12/13, YB Level

2:00 p.m. - 3:00 p.m. Oracle Fusion Middleware Management Marriott Hotel,Salon 12/13, YB Level

3:30 p.m. - -4:30 p.m. Provisioning, Patch Automation, and Configuration Management Pack Marriott Hotel,Salon 12/13, YB Level

Wednesday September 22, 2010

4:45 p.m. - 5:45 p.m. Database and Application Testing Marriott Hotel,Salon 12/13, YB Level

4:45 p.m. - 5:45 p.m. Oracle Application Mgmt. Pack for Oracle E-Business Suite: Monitor/Clone Marriott Marquis, Nob Hill

Thursday September 23, 2010

9:00 a.m. - 10:00 a.m. Database Performance Diagnostics and Tuning Marriott Hotel,Salon 12/13, YB Level

10:30 a.m. - 11:30 a.m. Oracle Fusion Middleware Management Marriott Hotel,Salon 12/13, YB Level

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Oracle Enterprise Manager DemogroundsD E M O T I T L E L O C A T I O N

Oracle Real Application Testing: Database Replay Moscone West

Oracle Real Application Testing: SQL Performance Analyzer Moscone West

Self-Managing Database: Automatic Performance Diagnostics Moscone West

Self-Managing Database: Automatic Fault Diagnostics Moscone West

Self-Managing Database: Automatic Application and SQL Tuning Moscone West

Application Quality Management: Application Testing Suite Moscone South - S022

Real User Monitoring with Oracle Enterprise Manager Moscone South - S021

Siebel CRM Application Management Moscone South - S024

Real User Monitoring with Oracle Enterprise Manager Moscone West

Oracle WebLogic Server Management and Java Diagnostics Moscone West

SOA Management with Oracle Enterprise Manager Moscone West

Oracle Business Transaction Management Moscone West

Push Button Provisioning and Patch Automation Moscone West

Smart Configuration Management Moscone West

Oracle Enterprise Manager Ops Center Moscone West

Managing the Enterprise Private Cloud Moscone West

System Management, My Oracle Support, and Oracle Enterprise Manager Moscone West

Self Managing Database: Change Management for DBAs Moscone West

Oracle Enterprise Manager: Complete Datacenter Management Moscone West

Self-Managing Database: Data Masking for DBAs Moscone West

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