Session id: 40170

The Self-managing Database: Proactive Space and Schema Object Management

Amit GaneshDirector,

Data, Space and Transaction ProcessingOracle Corporation

Agenda

Proactive Space Management– Alerts– Size estimation and growth trending– Segment Advisor and Shrink

Proactive Undo Management– Alerts– Auto-sizing– Auto-tuning

Automatic Space Management

Oracle9iNo external space fragmentations

– Locally Managed Tablespace

No space allocation contention

– Automatic Segment Space Management

No Rollback Segments– Automatic Undo

Management Intelligent Infrastructure

Application & SQLManagement

System ResourceManagement

SpaceManagement

Backup & RecoveryManagement

StorageManagement

Database Management

Oracle Database 10g –Self-Managing Database

Intelligent Infrastructure

Application & SQLManagement

System ResourceManagement

SpaceManagement

Backup & RecoveryManagement

StorageManagement

Database ManagementDatabase

Control

10g: Always working for you

Collects continuouslyRecords periodically to diskLearns from historical dataAdapts to changing workloadAlerts DBA when problems occurAdvises proactively on problems

Integrated with the Enterprise Manager

Proactive Space

Management

Proactive Space Management in 10g

Growth Trending 0

102030405060708090

1st Qtr 2nd Qtr 3rd Qtr 4th Qtr

Size Estimation$$

SegmentAdvisor

TablespaceAlertsShrink

Add fileRe-org/ rebuildResumable

OperationsOperations

PlanningPlanning

ActionsActions

Object Size Estimation

Tablespace Alerts

Database GeneratedWarning, CriticalOut of the box

Tablespaces can be provisioned with more disk space before out-of-space conditions occur

Tablespace Thresholds

85% Warning97% Critical

Alert

97% Critical97% Critical

85% Warning85% Warning

Add files

Freeing up space

Add FilesAdd Files

Free up spaceFree up space

Locally Locally Managed Managed

TablespaceTablespace

Resolve SpaceResolve Space

ProblemProblem

Alert Computation

Read only/Offline tablespaces: Do not setup alertsTemporary tablespace: Threshold corresponds to space currently used by sessions.Undo tablespace: Threshold corresponds to space used by active and unexpired extents.AUTOEXTENSIBLE files: Threshold is based on the maximum file size.

MMON

85% Warning

97% Critical

Check every 10 mns

Alert

Alert Cleared

Cleared

In-Memory

Calculation

Threshold Alert Tracking

SCNt210MB50MBSCNt1 60MB100MBFile1

File2

Filen

…

…

File SizeAllocated Space

Change SCN

…

Instance1

SCNt210MB50MBSCNt1 60MB100MBFile1

File2

Filen

…

……

Instance2

MMON MMON

Data aggregated

through GV$

Tablespace Size: 150M Allocated: 70M File1 File2

Tablespace

Setting Thresholds Using EM

Changing database default thresholdsChanging a particular tablespace thresholds

– Directly in the context of the tablespace– From the Edit Metric Thresholds page

Tablespace Threshold Page

Receiving Alerts in EM

Growth Trend Report

Based on Automatic Workload Repository DataIndicates past growth trend and predicts future growth pattern

Growth Trend Report

Segment Advisor

Determines whether an object is a good candidate for a shrink operation

– Based on unused space that can be released

– Considers estimated future space requirements

EM allows you to apply the recommended shrinkCan be invoked at the segment or tablespace level

Segment Shrink

HWM

ShrinkOperation

Data UnusedSpace

UnusedSpace

Reclaimed Space

ShrinkShrink

OperationOperationOnline and Online and

InIn--placeplace

HWM

Benefits

Online & In-place Faster access

ShrunkSegment

Better space utilization

Candidate Segments Auto Segment Space Managed

Tablespace

Tables

IOTs

MaterializedViews

LOBs

Indexes

Row MovementEnabled

Dependency Maintenance

DBA

Shrink

Index

Table

Indexes are maintained

Shrink

Trigger

Triggers are not fired

How Can I Shrink Segments?ALTER … SHRINK SPACE [CASCADE]

ALTER TABLE employees SHRINK SPACE CASCADE;

ALTER TABLE employees ENABLE ROW MOVEMENT; 1

2

TABLE INDEX MATERIALIZED VIEW MATERIALIZED VIEW LOG

MODIFY PARTITION MODIFY LOBMODIFY SUBPARTITION

How Does it Work?ALTER TABLE employees SHRINK SPACE COMPACT; 1

HWM

HWM

HWM

ALTER TABLE employees SHRINK SPACE; 2

EM Interface

Space Management : Before and Now

Oracle10G1. Launch Segment Advisor to

advise on which object(s) to shrink

2. Accept the recommendations to shrink the objects online and in-place

Before

Check to see which objects in the tablespace have pockets of wasted space due to deletion:

1. Create a script that looks at DBA_TABLES view to compare the total space allocated for each object (BLOCKS * DB_BLOCK_SIZE) in a tablespace to the estimated space used by the object (AVG_ROW_LEN * NUM_ROWS)

(assumes objects have been analyzed)2. Review script output and identify target objects for

reorganization3. Identify/Create “scratch” tablespace4. For each object to be reorganized, use the Enterprise

Manager Reorg wizard to recreate each object along with its dependencies

Scenario: Reclaim Wasted Space

Proactive Undo

Management

Oracle Database 10g

Auto-sizing Undo TablespaceAuto-tuning Undo RetentionProactive Monitoring Undo Advisor

Auto-sizing Undo Tablespace

A self-learning system– Create Undo tablespace with autoextensible files

– Run your workload

– Done!

(undo tablespace size adapts to the application)

Auto-tuning Undo Retention

OLTP DSS

0

2000

4000

6000

TimeT

un

ed

UR

, s

ec

on

ds

Tuned URQuery Length

Before Oracle 10g: Auto-tuning

Small RBS/UR = 15 min

Large RBS/UR = 5 hrs

Proactive Monitoring: AlertsOut of Undo Space AlertLong query warning Alert

Out of space Critical

Out of space Warning

ORA-1555 Failure

7:10…

7:00am 7:20 7:30 7:40

Undo Advisor

Automatically analyzes the undo usage to advice optimal:

– Undo tablespace size to support your longest running query

– Undo tablespace size for a given undo retention period to support Undo based Flashback toolset

Undo Home: Automatic Advice

Undo Advisor: What if?

Summary

Self-management engineered into the core of Oracle Database 10gSelf-management through:

– Auto-sizing and size estimation– Built-in statistics gathering– Server-driven Alerts– Automatic Advisers– Auto-tuning to adapt to changing workload– Integration with the Enterprise Manager

Next Steps….Recommended sessions

– The Self-Managing Database : Automatic Health Monitoring (Thursday, Sept. 11, 11 AM)

– Enterprise Manager : Scalable Oracle Management (Thursday, Sept. 11, 1 PM)

Recommended demos and/or hands-on labs– Oracle Database 10g : Manage the Oracle Environment

Hands-On Lab– Campground Demo : “The Self-Managing Database: Space

Management”Relevant web sites to visit for more information

– http://otn.oracle.com/products/manageability/database/content.html

Reminder: Please complete the OracleWorld online session survey

Session # 40170

Thank you.

Q U E S T I O N SQ U E S T I O N SA N S W E R SA N S W E R S