Oracle8 Server Migration
Release 8.0
A54650_01

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1
Migration Overview

This chapter gives an overview of the procedures required to migrate a pre-Oracle8 database to Oracle8.

These migration procedures transform an existing pre-Oracle8 database system (including associated applications) into an Oracle8 database system. The Oracle8 Server is compatible with all earlier Oracle versions and releases. Therefore, databases transformed using the migration processes described in this book can work in the same manner as in earlier versions and, optionally, can also be used with new Oracle8 functionalities.

Several preparatory steps are required before you migrate the current production database. After migrating a database, you should then perform several additional test steps to test the migration. Additional steps may be used to add new Oracle8 functionalities to existing pre-Oracle8 applications.

The following topics are discussed in this chapter:

Migration to Oracle8: Overview of Steps

Before attempting to migrate a database, you should understand the requirements and procedures involved with each step of the migration process. The migration steps are generic and do not depend on a specific operating system (possibly except for one or two platform-specific details identified in one or more platform-specific Oracle8 Installation Guides).

Careful planning and Oracle8 tools can ease the process of migrating a database to Oracle8. The Oracle8 Migration Utility makes the process of migrating an entire database as simple as possible. The Export/Import and SQL copy utilities provide for piecemeal migration of parts of the database.

The migration process can be summarized under the following six steps:

After the following brief outlines of these migration steps, the chapters in this book explain each migration step in detail.

Step 1: Prepare to Migrate

Become familiar with the features of the Oracle8 database.
Decide which migration method to use, based on comparisons of the current production database, your migration objectives, and the behavior and capabilities of available migration methodologies.
Estimate and secure the system resources required for the migration.
Develop a plan for testing the Oracle8 test database and also for later testing the newly migrated Oracle8 production database.

Step 2: Test the Migration Process

Test the chosen migration method by using an Oracle7 test source database in an environment created to test migration without interfering with the actual Oracle7 source database.

Step 3: Test the Migrated Test Database

Perform the planned tests on the Oracle7 source database and on the Oracle7 test database that was migrated to Oracle8.
Compare results, noting anomalies between test results on the Oracle7 source database and on the Oracle7 test database migrated to Oracle8.
Repeat Step 1, Step 2, and (the first parts of) Step 3, as necessary.
After the migrated test database has passed the planned tests and works with the applications, proving the migration process, continue with Step 4.

Chapter 2, "Preparing to Migrate", provides detailed information on Steps 1 through 3.

Step 4: Prepare and Preserve the Source Database

Prepare the current production database as appropriate to ensure that its migration to Oracle8 will be complete and correct.
Schedule the downtime required for backing up and migrating the pre-Oracle8 production database to Oracle8.
Produce a full backup of the current source database. This step is required only if the Migration Utility is used for the migration.

Step 5: Migrate the Source Database

Use the chosen migration method to migrate the pre-Oracle8 source database to Oracle8.
After migrating the source database, make a complete backup of it.

Chapter 3 describes Steps 4 and 5 using the Migration Utility. Chapter 4 describes Steps 4 and 5 using the Export/Import utilities. Chapter 5 describes the backup procedure after migration.

If you are migrating a pre-Oracle8 database system that has Advanced Replication installed, you must also refer to Oracle8 Server Replication, Appendix B, "Migration and Compatibility."

Step 6: Tune and Adjust the New Production Database

Make tuning adjustments as needed to ensure performance of the new production database is as good as, or better than, the source database. Chapter 5 describes these tuning adjustments.
Determine which new features of the Oracle8 database are appropriate to use with your data and update your applications accordingly.
Develop new database administration procedures as needed.
Do not migrate production users to the Oracle8 database until all applications have been tested and demonstrated to operate properly. Chapter 6 describes details that may be important for updating applications.

Role of the Database Administrator During Migration

Typically the database administrator (DBA) is responsible for ensuring the success of the migration process. The DBA typically becomes involved in each step of the process, except for steps that are concerned with testing applications in the target database.

The specific DBA duties typically include:

meeting with everyone involved in the migration process and clearly defining their roles during migration
performing test migrations
scheduling the test and production migration process
making backups of the Oracle7 production database to be migrated
accomplishing the actual migration
making backups of the newly migrated Oracle8 production database

Users should not have access to the migrated Oracle8 database until after all applications have been tested and shown to operate properly.

Role of the Application Developer During Migration

The application developer is responsible for ensuring that applications designed for the Oracle7 source database work the same way with the migrated Oracle8 target database. Application developers often test applications against the migrated Oracle8 database and decide which available new features of Oracle8 should be implemented.

Before migrating the Oracle7 production database, the DBA or application developer should install an Oracle8 test database. Applications can then be tested and modified, if necessary, to work with their original (or enhanced Oracle8) functionality with the Oracle8 database.

The application developer should use all of the following sources to identify differences in the migrated Oracle8 database that could affect particular applications. Use these differences to help guide any modifications that need to be made in existing applications.

Chapter 6, "Upgrading Oracle7 Applications", describes the changes needed to enable existing applications (that access an Oracle7 database) to access an Oracle8 database. Guidance for upgrading Oracle7 applications to take advantage of Oracle8 functionalities also is given.
Appendix A describes enhancements in Oracle8.
Appendix C lists changed data dictionary views an application might depend on and SQL reserved and key words for Oracle8.
Oracle8 Parallel Server Concepts & Administration and Oracle8 Server SQL Reference contain descriptions of changes and functionalities in Oracle8.
For a pre-Oracle8 database system that has Advanced Replication installed, you must also refer to Oracle8 Server Replication, Appendix B, "Migration and Compatibility."

Oracle8 provides features that aid in upgrading existing applications to Oracle8:

Net8 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 versions and releases.