|Oracle9i Database Migration
Release 1 (9.0.1)
Part Number A90191-02
This chapter describes upgrading your current applications and covers the following topics:
You do not need to modify existing Oracle7 and version 8 applications that do not use new Oracle9i features. Existing applications running against an Oracle9i database function the same as they did on prior releases and achieve the same, or enhanced, performance.
Many new features and enhancements are available after migrating or upgrading to Oracle9i. Some of these features provide added functionality, while others provide improved performance. Before you upgrade your applications, you should review these new features to decide which ones you want to use.
Oracle9i Database New Features for information about new features available in Oracle9i.
There may be compatibility issues between different releases of Oracle that could affect your applications. These compatibility issues result from differences in the Oracle database server in various releases. Also, in each new release of Oracle, new Oracle reserved words may be added, changes may be made to initialization parameters, and changes may be made to the data dictionary.
When you upgrade or migrate your Oracle database server to a new release, make sure that your applications do not use any Oracle reserved words, that your applications are compatible with the initialization parameters of the server, and that your applications are compatible with the data dictionary of the server. Finally, a new release of Oracle software may require certain operating system versions or certain patch sets to be applied.
SQL*Net version 2, Net8, and Oracle Net Services work with various Oracle releases. Thus, Oracle7, version 8, and Oracle9i databases can communicate by using SQL*Net version 2, Net8, and Oracle Net Services. SQL*Net version 1, however, uses a different network addressing scheme and cannot be used with release 8.0 and higher.
The upgrade path is very similar for precompiler and OCI applications. This section guides you through your upgrade options for these applications and notes differences between precompiler and OCI applications whenever necessary.
Create a test environment before you upgrade your production environment. Your test environment should include your upgraded application and the Oracle9i database. Also, your test environment should provide a realistic test of your application.
To understand your options for upgrading precompiler and OCI applications, you first need to understand the type of software upgrade you are performing and your client/server configuration.
Three types of upgrades are possible for both client and server Oracle software.
The upgrade changes the first digit of the release number.For example, upgrading from any Oracle7 release to any version 8 release is a version release upgrade.
The upgrade changes the second digit of the release number. For example, upgrading from any 8.0 release to any 8.1 release is a feature release upgrade.
The upgrade changes the third digit of the release number. For example, upgrading from release 8.1.6 to release 8.1.7 is a maintenance release upgrade.
Your precompiler and OCI applications run on the client in a client/server environment, where the Oracle database server is the server. You may use one or more of the following client/server configurations in your environment.
The client software and the server software are on different computers, and they are connected through a network. The client and server environments are separate.
The client software and the server software are on the same computer, but they are installed in different Oracle home directories. Again, the client and server environments are separate.
The client software and server software are installed in the same Oracle home on the same computer. In this case, any upgrade of the server software is also an upgrade of the client software.
Oracle9i Database Concepts and Oracle9i Heterogeneous Connectivity Administrator's Guide for more information about client/server environments.
This section covers compatibility rules that apply when you upgrade Oracle server software or Oracle client software. The rules are based on the type of software upgrade you are performing and on your client/server configuration.
The following sections contain compatibility rules for the following type of upgrades:
The following rules apply when you upgrade the Oracle server software.
If your client and server are on different computers or are in different Oracle home directories on the same computer, and you upgrade the Oracle server software without changing the client software, then you do not need to precompile, compile, or relink your applications. In these cases, the client software is separate from the server software and will continue to function against the server.
However, if your applications are using the same Oracle home as the Oracle database server, then your server upgrade also upgrades your client software, and you must follow the rules in "Upgrading the Oracle Client Software".
When you run a precompiler or OCI application against a database server, Oracle Corporation recommends that the release of the database server software be equal to or higher than the client software release, but this configuration is not strictly required. For example, if your Oracle client software is release 8.0.6, then your Oracle server software should be release 8.0.6 or higher to run a precompiler application on the client against the server.
For OCI, Oracle7 client software can run against a release 8.0 or higher Oracle server, and release 8.0 or higher client software can run against an Oracle7 server. However, if the client software is version 6, then the server software must be Oracle7 or lower; in this case, the server software cannot be release 8.0 or higher. Similarly, if the client software is release 8.0 or higher, then the server software must be Oracle7 or higher; in this case, the server software cannot be version 6. Again, if a release 8.0 or higher client is running against an Oracle7 server, then the application cannot use features available in release 8.0 and higher, including object capabilities.
Oracle Corporation recommends that you upgrade your client software to match the current server software. For example, if you upgrade your Oracle database server to release 9.0.1, then Oracle Corporation recommends upgrading the client software to release 9.0.1 as well. Keeping the server and client software at the same release number ensures the maximum stability for your applications. In addition, the latest Oracle client software may provide added functionality and performance enhancements that were not available with previous releases.
The following rules apply when you upgrade the Oracle client software.
The code generated by precompiler applications can be linked with a release of the client library that is equal to or higher than the server release. In addition, Oracle7 and release 8.0 and higher SQLLIB function calls cannot be mixed in the same application and the same transaction.
OCI applications can be linked with a version of the OCI runtime library that is equal to or higher than the version of the OCI library with which the application was developed.
For statically-linked applications, when you perform any type of upgrade of the client software, you do not need to relink your precompiler and OCI applications. However, relinking is recommended because it may improve performance.
When you perform a maintenance release upgrade of the client software, you do not need to relink your applications. Your application continues to function normally without relinking. For example, if you upgrade the client software from release 8.1.6 to release 8.1.7, then you do not need to relink your applications.
When you perform a version or feature release upgrade of your client software, you do not need to relink your dynamically-linked precompiler and OCI applications. However, relinking is recommended because it may improve performance.
You have the following four options for upgrading your precompiler and OCI applications:
Leave the application unchanged. Do not relink, precompile, or compile the application, and do not change the application code. The application will continue to work against an Oracle9i database.
Relink the application with the new Oracle9i libraries. Do not precompile or compile the application and do not change the application code.
Precompile and/or compile and then relink the application using the new Oracle9i software. Do not change the application code.
Change the application code to use new Oracle9i features. Then, precompile and/or compile and then relink the code.
These options are listed in order of increasing difficulty and increasing potential benefits. That is, Option 1 is the least difficult option, but it offers the least potential benefits, while Option 4 is the most difficult option, but it offers the most potential benefits. These options are discussed in the following sections.
You can leave the application unchanged, and it will continue to work with an Oracle9i database. The major advantage to this option is that it is simple and easy. In addition, this option requires the least amount of administration, because you do not need to upgrade all of your client computers. If you have a large number of client computers, then avoiding the administrative costs of upgrading all of them can become very important.
The major disadvantage to this option is that your application cannot use the new features that are available in Oracle9i. In addition, your application cannot leverage some of the possible performance benefits of Oracle9i.
When you perform certain types of upgrades, you are required to relink your application with the new libraries. For example, if you perform a version or feature release upgrade of the client environment, then you must relink. See "Compatibility Rules for Applications When Upgrading Oracle Software" for information about the rules to follow when you upgrade Oracle software.
You can relink the application with the new Oracle9i libraries, without making any code changes and without recompiling. By relinking, your application may benefit from performance improvements that are available only with the new libraries. Remember that you should always relink the application in a test environment before you relink in your production environment.
You can precompile or compile the application with the new Oracle9i software, without making any code changes. This option requires that you install the new Oracle client software on each client computer. However, you only need to precompile or compile, and relink your application once, regardless of the number of clients you have. The advantages, however, can be quite large.
By recompiling, you perform a syntax check of your application code. Some problems in the application code that were not detected by previous releases of the Oracle software may emerge when you precompile or compile with the new Oracle software. Therefore, precompiling and compiling with the new software often helps you detect and correct problems in the application code that may have gone unnoticed before.
Also, recompiling affords maximum stability for your application, because you are sure that it works with the new Oracle software. Further, your environment is ready for new development using the latest tools and features available. In addition, you may benefit from performance improvements that are available with the new Oracle software only after you recompile and relink.
You can make code changes to your application to take advantage of new Oracle9i features. This option is the most difficult, but it can provide the most potential benefits. You gain all of the advantages described in Option 3. In addition, you also benefit from changes to your application that may leverage performance and scalability benefits available with Oracle9i. Further, you can add new features to your application that are available only with the new release of Oracle9i.
Become familiar with the new Oracle9i features by reading Oracle9i Database New Features. Also, consult the Oracle documentation for your development environment so that you understand how to implement the features you want to use. For the precompilers, see Pro*C/C++ Precompiler Programmer's Guide and Pro*COBOL Precompiler Programmer's Guide. For OCI, see Oracle Call Interface Programmer's Guide.
When you have decided on the new features you want to use, change the code of your application to use these features. Follow the appropriate instructions in the following sections based on your development environment:
Complete the following steps to change your precompiler application to use Oracle9i features:
Complete the following steps to change your OCI application to use Oracle9i features:
To use SQL*Plus release 8.0 and higher, a release 8.0 or higher database, and PL/SQL release 8.0 and higher functionality, complete the following steps:
SET COMPATIBILITY V7, then change it to
SET COMPATIBILITY NATIVE, or remove the line so that the default setting is used. In Oracle9i, the default setting is
glogin.sqlfiles and change any
SET COMPATIBILITY V7line found to
SET COMPATIBILITY NATIVE.
Forms applications run the same on Oracle7, version 8, and Oracle9i. However, review the new features described in Oracle9i Database New Features to determine whether any of the new Oracle9i features would be beneficial to your applications or might otherwise affect them. Information about the ways in which the Oracle9i features interact with forms and developer applications is provided in the Oracle Developer documentation set. Also, the Oracle Developer documentation for your operating system contains instructions for upgrading your forms or developer applications.