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Managing Database Storage Structures

Managing Database Storage Structures. Objectives. After completing this lesson, you should be able to do the 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

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Managing Database Storage Structures

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  1. Managing Database Storage Structures

  2. Objectives • After completing this lesson, you should be able to do the 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)

  3. Database Tablespace Segment Extent Oracle datablock Storage Structures Logical Physical OS file OSblock

  4. How Table Data Is Stored Columns Blocks Table A Table B Rows Segment Segment Table Tablespace Extent Row piece

  5. Anatomy of a Database Block Block header Growth Free space Row data

  6. Database Tablespace Data files Tablespaces and Data Files • The Oracle database stores data logically in tablespaces 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 onetablespace and one database • Are a repository for schema object data

  7. 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.

  8. Creating a New Tablespace

  9. Storage for Locally Managed Tablespaces

  10. Tablespaces in the Preconfigured Database • SYSTEM • SYSAUX • TEMP • UNDOTBS1 • USERS • EXAMPLE

  11. Altering a Tablespace

  12. Actions with Tablespaces

  13. Dropping Tablespaces

  14. Viewing Tablespace Information

  15. 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)

  16. 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 challenges Application Database Filesystem ASM Volumemanager Operating system

  17. 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

  18. ASM: Concepts ASMdisk group Database ASM file Data file Tablespace Segment ASM disk Extent File system file orRaw device Allocation unit Oracle datablock Physicalblock

  19. 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

  20. Practice Overview:Managing Database Storage Structures • This practice covers the following topics: • Creating tablespaces • Gathering information about tablespaces

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