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5Copyright 2005, Oracle. All rights reserved.

Managing Database Storage Structures


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5-2 Copyright 2005, Oracle. All rights reserved.

Objectives

After completing this lesson, you should be able to dothe following: Describe how table row data is stored in blocks

Define the purpose of tablespaces and data files Create and manage tablespaces Obtain tablespace information Describe the main concepts and functionality

of Automatic Storage Management (ASM)


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Storage Structures

Database

Tablespace

Segment

Extent

Oracle datablock

Logical Physical

OSblock

OS file


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How Table Data Is Stored

Tablespace

Table A Table B

SegmentSegment

Rows

Columns

Table

Blocks

Row piece Extent


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Anatomy of a Database Block

Block header

Free space

Row data

Growth


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Tablespaces and Data Files

The Oracle database stores data logically intablespaces and physically in data files. Tablespaces:

Can belong to only one database Consist of one or more data files Are further divided into logical units of storage

Data files: Can belong to only one

tablespace and one database Are a repository for schema

object data

Database

Tablespace

Data files


7/265-7 Copyright 2005, Oracle. All rights reserved.

Space Management in Tablespaces

Locally managed tablespace: Free extents are managed in the tablespace. A bitmap is used to record free extents. Each bit corresponds to a block or group of blocks. The bit value indicates free or used extents. The use of locally managed tablespaces is

recommended. Dictionary-managed tablespace:

Free extents are managed by the data dictionary. Appropriate tables are updated when extents are

allocated or unallocated. These tablespaces are supported only for backward

compatibility.



Creating a New Tablespace



Creating a New Tablespace(Notes Only Slide)



Storage for Locally Managed Tablespaces



Storage for Locally Managed TablespacesFull Notes Page



Tablespaces in the PreconfiguredDatabase

SYSTEM

SYSAUX

TEMP

UNDOTBS1

USERS

EXAMPLE



Tablespaces in thePreconfigured Database

Full Notes Page



Altering a Tablespace



Altering a TablespaceFull Notes Page



Actions with Tablespaces



Actions with TablespacesFull Notes Page



Dropping Tablespaces



Viewing Tablespace Information



Where We Are

Using tablespaces to separate data Creating various types of tablespaces Managing tablespaces

Obtaining tablespace information Describe the main concepts and functionality

of Automatic Storage Management (ASM)



What Is Automatic Storage Management?

Is a portable and high-performancecluster file system

Manages Oracle database files

Spreads data across disksto balance load Mirrors data Solves many storage

management challengesASM

Filesystem

Volumemanager

Application

Database

Operating system



ASM: Key Features and Benefits

Stripes files, but not logical volumes Provides online disk reconfiguration and dynamic

rebalancing

Allows for adjustable rebalancing speed Provides redundancy on a per-file basis Supports only Oracle database files Is cluster aware

Is automatically installed



ASM: Concepts

Database

Tablespace

Segment

Extent

Oracle datablock

Data file

Physicalblock

ASM disk

ASM file

Allocation unitFile system

fileor

Raw device

ASMdisk group



Summary

In this lesson, you should have learned how to: Describe how table row data is stored in blocks Define the purpose of tablespaces and data files

Create and manage tablespaces Obtain tablespace information Describe the main concepts and functionality of

ASM, such as:

Disk mirroring Dynamic rebalancing ASM disk groups


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Practice Overview:Managing Database Storage Structures

This practice covers the following topics: Creating tablespaces Gathering information about tablespaces

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