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Introduction

This chapter includes an overview of database migration as well as information about running multiple releases of Oracle. This chapter also provides information on changing the word size of your database during an upgrade or downgrade.

This chapter covers the following topics:

• Terminology
• Overview of Database Migration
• Running Multiple Oracle Releases
• Using Optimal Flexible Architecture (OFA)
• Changing Word Size
• Rolling Upgrades
• Deinstalling Options

Terminology

The following terms are used throughout this document:

Oracle Releases

The instructions in this document describe moving between different releases of the Oracle database server. Figure 1-1 describes what each part of a release number represents.

Figure 1-1 Example of an Oracle Release Number

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When a statement is made in this book about a major database release number, the statement applies to all releases within that major database release. References to Oracle9i include all releases in release 9.0 and release 9.2; references to version 8 include all releases in release 8.0 and release 8.1. References to version 7 include all Oracle7 releases in release 7.0, release 7.1, release 7.2, and release 7.3.

Similarly, when a statement is made in this book about a maintenance release, the statement applies to all component specific and platform specific releases within that maintenance release. So, a statement about release 9.0.1 applies to release 9.0.1.1, release 9.0.1.1.2, and all other platform specific releases within release 9.0.1.

Database Migration

Database migration refers to the collection of processes and procedures for converting the data in an Oracle database to reflect a particular release of the Oracle database server. Database migration includes the following:

• The upgrade process, which upgrades a database to a new Oracle release.

  See Also: Chapter 3, "Upgrading a Database to the New Oracle9i Release" for information about the upgrade process

• The downgrade process, which downgrades a database back to the Oracle release of the database prior to the upgrade.

  See Also: Chapter 7, "Downgrading a Database Back to the Previous Oracle Release" for information about the downgrade process

  Note: Since this book documents upgrading and downgrading between different releases of Oracle, this definition of database migration is appropriate. However, other Oracle documentation may use a broader definition of the term migration; for example, in some cases, migration may describe the process of moving data from a non-Oracle database into an Oracle database.

Overview of Database Migration

This section includes an overview of the major steps required to upgrade an existing Oracle database to the new Oracle9i release. Oracle9i is compatible with all earlier Oracle releases. Therefore, databases upgraded using the procedures described in this book can work in the same manner as in earlier releases and, optionally, can leverage new Oracle9i functionality.

Several preparatory steps are required before you upgrade your current production database. After the upgrade, you should perform several additional test steps. Other procedures enable you to add new Oracle9i functionality to existing applications.

Overview of Upgrade Steps

Before you upgrade a database, you should understand the major steps in the upgrade process. These steps apply to all operating systems, with the possible exception of a few operating system-specific details identified in your operating system-specific Oracle documentation.

Figure 1-2 Major Upgrade Steps

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Careful planning and use of Oracle9i tools can ease the process of upgrading a database to the new Oracle9i release. You can use one of the following methods to upgrade a database:

• The Database Upgrade Assistant is the easiest way to upgrade a database. You can choose to run the Database Upgrade Assistant either during the installation of the new Oracle9i release or after installation is complete.

  Note: The Database Upgrade Assistant is the preferred method of upgrading a database; Oracle Corporation highly recommends using the Database Upgrade Assistant to upgrade to the new Oracle9i release.

• A manual upgrade is more complicated but provides finer control over the process of upgrading a database.
• Export/Import and data copying enable piecemeal migration of parts of a database.

The following sections contain a brief outline of the major steps shown in Figure 1-2. The purpose of these descriptions is to familiarize you with the major steps in the upgrade process. For detailed instructions, refer to the appropriate chapters in this book.

Step 1: Prepare to Upgrade

• Become familiar with the features of the new Oracle9i release. See Oracle9i Database New Features for an overview of these features.
• Decide which upgrade method to use, based on considerations involving your current production database.
• Estimate and secure the system resources required for the upgrade.
• Develop a plan for testing the upgrade with an Oracle9i test database and a plan for testing the upgraded Oracle9i production database.
• Prepare a backup strategy so that you can recover quickly from any unexpected problems or delays.

Step 2: Test the Upgrade Process

• Perform a test upgrade using a test database. The test upgrade should be conducted in an environment created for testing and should not interfere with the actual production database.

Step 3: Test the Upgraded Test Database

• Perform the tests you planned in Step 1 on the test database and on the test database that was upgraded to the new Oracle9i release.
• Compare results, noting anomalies between test results on the test database and on the upgraded database.
• Investigate ways to correct any anomalies you find and then implement the corrections.
• Repeat Step 1, Step 2, and the first parts of Step 3, as necessary, until the test upgrade is completely successful and works with any required applications.

Chapter 2, "Preparing to Upgrade" provides detailed information about Steps 1 through 3.

Step 4: Prepare and Preserve the Production Database

• Prepare the current production database as appropriate to ensure that its upgrade to the new Oracle9i release will be successful.
• Schedule the downtime required for backing up and upgrading the production database.
• Perform a full backup of the current production database.

Step 5: Upgrade the Production Database

• Upgrade the production database to the new Oracle9i release.
• After the upgrade, perform a full backup of the production database and perform other post-upgrade tasks.

Chapter 3 describes Steps 4 and 5 when using the Database Upgrade Assistant and when performing a manual upgrade. Chapter 8 describes Steps 4 and 5 when using the Export/Import utilities. Chapter 4 describes the backup procedure after the upgrade and other post-upgrade tasks.

Step 6: Tune and Adjust the New Production Database

• Tune the new Oracle9i production database. The new Oracle9i production database should perform as good as, or better than, the database prior to the upgrade. Chapter 4 describes these tuning adjustments.
• Determine which features of the new Oracle9i release you want to use and update your applications accordingly.
• Develop new database administration procedures as needed.
• Do not upgrade production users to the new Oracle9i database until all applications have been tested and operate properly. Chapter 6 describes considerations for updating applications.

During the upgrade, multi-versioning can be a useful feature because you can keep multiple copies of the same database on one computer. You can use the existing release as your production environment while you test the new release.

Role of the Database Administrator During the Upgrade

Typically, the database administrator (DBA) is responsible for ensuring the success of the upgrade process. The DBA is usually involved in each step of the process, except for steps that involve testing applications on the upgraded database.

The specific DBA duties typically include the following:

• Meeting with everyone involved in the upgrade process and clearly defining their roles
• Performing test upgrades
• Scheduling the test and production upgrades
• Performing backups of the production database
• Completing the upgrade of the production database
• Performing backups of the newly upgraded Oracle9i production database

Role of the Application Developer During the Upgrade

The application developer is responsible for ensuring that applications designed for the current database work correctly with the upgraded Oracle9i database. Application developers often test applications against the upgraded Oracle9i database and decide which new features of Oracle9i should be used.

Before upgrading the production database, the DBA or application developer should install an Oracle9i test database. Then, the application developer can test and modify the applications, if necessary, until they work with their original (or enhanced Oracle9i) functionality.

The following references provide information about identifying differences in the upgraded Oracle9i database that could affect particular applications. Application developers can use these differences to guide modifications to existing applications.

• Chapter 5, "Compatibility and Interoperability" describes compatibility and interoperability issues that may result because of differences in releases of Oracle.
• Chapter 6, "Upgrading Your Applications" describes the changes required to enable existing applications to access an Oracle9i database and provides guidance for upgrading applications to take advantage of Oracle9i functionality.
• Appendix A, "Changes to Initialization Parameters and the Data Dictionary" lists obsolete and deprecated initialization parameters and data dictionary views.
• Appendix B, "Upgrade Considerations for Oracle Net Services" provides instructions for upgrading SQL*Net and Net8 to Oracle Net Services.
• Appendix E, "Database Migration and Compatibility for Replication Environments" provides instructions for upgrading a database that has Oracle Replication installed.
• Oracle9i Database New Features describes the features available in the new Oracle9i release
• Oracle9i Real Application Clusters Concepts and Oracle9i SQL Reference contain descriptions of changes and new Oracle9i functionality.
• Oracle9i Application Developer's Guide - Fundamentals, Oracle9i Application Developer's Guide - Large Objects (LOBs), and Oracle9i Application Developer's Guide - Advanced Queuing provide information about planning and implementing applications.

Oracle9i includes features that aid in upgrading existing applications to Oracle9i, for example:

• Oracle Net and SQL*Net V2 support communication between Oracle versions.
• The programming interface is unchanged between Oracle versions.
• Oracle's backward compatibility accommodates small incompatibilities between different releases.

Running Multiple Oracle Releases

You can run different releases of Oracle on the same computer at the same time. However, each release can only access a database that is consistent with its release. For example, if you have Oracle8i and Oracle9i installed on the same computer, then the Oracle8i server can access Oracle8i databases but not Oracle9i databases, and the Oracle9i server can access Oracle9i databases but not Oracle8i databases. The following sections provide general information about running multiple releases of Oracle.

Install Databases in Multiple Oracle Homes on the Same Computer

You can install Oracle7, Oracle8, Oracle8i, and Oracle9i databases in multiple (separate) Oracle homes on the same computer and have Oracle7, Oracle8, Oracle8i, and Oracle9i clients connecting to any or all of the databases.

Install Databases in Multiple Oracle Homes on Separate Computers

You can install Oracle7, Oracle8, Oracle8i, and Oracle9i databases in multiple (separate) Oracle homes on separate computers and have Oracle7, Oracle8, Oracle8i, and Oracle9i clients connecting to any or all of the databases.

Upgrade a Database to the Current Release

You can upgrade an Oracle7, Oracle8, Oracle8i, or Oracle9i database to the current Oracle9i release and have Oracle7, Oracle8, Oracle8i, and Oracle9i clients connecting to the upgraded database. You cannot upgrade the database in the same Oracle home.

Upgrade Clients to the Current Release

You can upgrade any or all of your Oracle7, Oracle8, Oracle8i, or Oracle9i clients to the current Oracle9i release. You can also upgrade your Oracle7, Oracle8, Oracle8i, or Oracle9i database to the current Oracle9i release at a later date.

Using Optimal Flexible Architecture (OFA)

Oracle Corporation recommends the Optimal Flexible Architecture (OFA) standard for your Oracle9i installations. The OFA standard is a set of configuration guidelines for efficient and reliable Oracle databases that require little maintenance.

OFA provides the following benefits:

• Organizes large amounts of complicated software and data on disk to avoid device bottlenecks and poor performance
• Facilitates routine administrative tasks, such as software and data backup functions, which are often vulnerable to data corruption
• Alleviates switching among multiple Oracle databases
• Adequately manages and administers database growth
• Helps to eliminate fragmentation of free space in the data dictionary, isolates other fragmentation, and minimizes resource contention.

If you are not currently using the OFA standard, then switching to the OFA standard involves modifying your directory structure and relocating your database files.

Changing Word Size

You can implicitly change the word size of your database during an upgrade or downgrade. A change in word size includes the following scenarios:

• You have 32-bit Oracle software installed on 64-bit hardware and want to change to 64-bit Oracle software.
• You have 64-bit Oracle software installed on 64-bit hardware and want to change to 32-bit Oracle software.

If you are changing word size during an upgrade or downgrade, then no additional action is required. The word size is changed automatically during either of these operations. However, if you want to explicitly change the word size within the same release, then follow the instructions in "Changing the Word Size of Your Current Release". For example, if you have the 32-bit installation of release 9.2 and you want to switch to the 64-bit installation of release 9.2, then you must complete this procedure.

The following information applies if you are switching from 32-bit hardware to 64-bit hardware or from 64-bit hardware to 32-bit hardware:

• You can switch from 32-bit hardware to 64-bit hardware and still use your existing 32-bit Oracle software without encountering any problems.
• If you want to switch from 64-bit hardware to 32-bit hardware, then you must first install 32-bit Oracle software before switching from 64-bit hardware to 32-bit hardware.

The on-disk format for database data, redo, and undo is identical for the 32-bit and 64-bit installations of Oracle. The only internal structural differences between the 32-bit and 64-bit installations are the following:

• The compiled format of PL/SQL is different. The instructions for how and when to recompile PL/SQL are provided in the appropriate chapters of this book.
• The storage format of user-defined types is based on the release of Oracle that created the database. The existing storage format will be transparently converted to the correct format when necessary. User-defined types include object types, REFs, varrays, and nested tables.

Rolling Upgrades

The term rolling upgrade refers to upgrading different databases or different instances of the same database in Oracle9i Real Application Clusters one at a time, without stopping the database. Oracle9i Real Application Clusters does not support rolling upgrades.

Deinstalling Options

If you want to deinstall old options when you upgrade to the new Oracle9i release, then use the Oracle Universal Installer to deinstall them. You can deinstall them before or after you upgrade, but you must use the release of the installer that corresponds with the items you want to remove.

For example, if you are running release 9.0.1 with Oracle Text installed, and you decide that you do not need this option when you upgrade to the new Oracle9i release, then you should deinstall Oracle Text in one of the following ways:

• Before you upgrade to the new Oracle9i release, use the release 9.0.1 Oracle Universal Installer to deinstall Oracle Text. Then, do not install Oracle Text when you install the new Oracle9i release.
• When you upgrade to the new Oracle9i release, install and upgrade Oracle Text. Then, use the Oracle Universal Installer in the new Oracle9i release to deinstall Oracle Text.

  Note: After you deinstall an option, extraneous data dictionary tables may remain in the database.

  See Also: Your operating system-specific Oracle documentation for information about using the Oracle Universal Installer