Less05 Storage Tb
Transcript of Less05 Storage Tb
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5Copyright 2005, Oracle. All rights reserved.
Managing Database Storage Structures
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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
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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.
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Creating a New Tablespace
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Creating a New Tablespace(Notes Only Slide)
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Storage for Locally Managed Tablespaces
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Storage for Locally Managed TablespacesFull Notes Page
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Tablespaces in the PreconfiguredDatabase
SYSTEM
SYSAUX
TEMP
UNDOTBS1
USERS
EXAMPLE
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Tablespaces in thePreconfigured Database
Full Notes Page
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Altering a Tablespace
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Altering a TablespaceFull Notes Page
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Altering a TablespaceFull Notes Page
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Actions with Tablespaces
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Actions with TablespacesFull Notes Page
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Dropping Tablespaces
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Viewing Tablespace Information
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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)
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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
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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
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ASM: Concepts
Database
Tablespace
Segment
Extent
Oracle datablock
Data file
Physicalblock
ASM disk
ASM file
Allocation unitFile system
fileor
Raw device
ASMdisk group
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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