Oracle9i New Features [Paperback]

Maximize the Potential of Oracle9i

Get the most out of Oracle9i using the precise information presented in this convenient resource, officially authorized by Oracle Corporation. Inside, you'll find full details on all the new Oracle9i features, including database administration and management improvements, architecture changes, performance enhancements, security advancements, and high-availability innovations. Find out how to take full advantage of all the new and improved Oracle9i capabilities, including:

• Database administration improvements, such as managed datafiles and resumable space management
• Enhanced availability and recoverability features, including Oracle Flashback Query and Oracle9i Data Guard
• Parameter and view changes
• Oracle9i XML Development Kits (XDKs) and iFS
• Expanded high-availability functions, including Oracle9i Real Application Clusters
• Advanced security capabilities, such as Virtual Private Database (VPD) and encryption tools
• National Language Support (NLS) and globalization support enhancements
• New data warehousing and online analytical processing capabilities
• New SQL and PL/SQL features

Welcome to the first chapter of Oracle9i New Features. This chapter is the beginning of your journey into Oracle9i’s new and enhanced features. Of course, DBAs want features and enhancements to make the management of their Oracle databases easier, quicker, and with as little impact on their users as possible. Oracle9i responds to this need with many new management features, and it is these features that we will address here.

The Compatibility Parameter
As we begin to review many of the new, changed, and enhanced features of Oracle9i, a word about the compatibilityparameter: this parameter, which is located in the database parameter file (init.ora), controls which database features you can, and cannot, use. It might well be a good idea when migrating to Oracle9i
to leave compatibilityset to the version of the database you are migrating from until you are comfortable with Oracle9i. This is because you will not be able to use the new features of Oracle9i with the compatibility parameter set to a value that is not 9i. This makes it easier if you find you need to roll back your database upgrade or migration, since you will not have taken advantage of some Oracle9i feature
that will have to be backed out before you can roll the database back to the previous version.
Also, certain database default actions (such as creating a tablespace) are different depending on the value of compatibility. Once you have migrated or upgraded to Oracle9i and you are comfortable with the new database, set the compatibleparameter to 9.0.0.0, and you can start using some of the new Oracle9i features that you will find inside this book.

Migration/Upgrade Notes
Generally, all operating systems support a direct migration from Oracle 7.2 or later to Oracle9i using the mig utility or the database migration assistant. Many platforms even support migration from Oracle 7.1. If you are running Oracle8i, then you will need to upgrade the database following your platform-specific instructions. This generally involves starting the 8i database under the 9i RDBMS software and running
an upgrade script. Please refer to your platform-specific documentation for exact instructions on migrating or upgrading to Oracle9i from your current Oracle version.

Oracle-Managed Datafiles (OMFs)
The first new Oracle9i feature you are going to learn about in this chapter are Oracle-Managed Datafiles(OMFs). OMFs give Oracle the ability to manage Oracle database files for you. OMFs are part of the Oracle9i move to make the Oracle database easier to manage. Previous to Oracle9i, when you dropped a tablespace, you would also have to remove the physical datafile associated with that tablespace. With Oracle9i, you can leave physical file management to the database itself, using OMFs. In this section, you will learn about the types of datafiles that are managed by this feature, and some of the benefits and restrictions of OMFs. Then you will learn how to configure your database to take advantage of OMFs, and you will find some examples of using OMFs.

OMF Uses, Rules, and Restrictions
In this section, you will learn about the uses, rules, and restrictions involved in using OMFs. First, we’ll look at the concept of using OMFs, when they should be used, and when they should not. Then we’ll move on to OMF management issues.

Introducing OMF
You can use OMF when creating database datafiles, tempfiles, online redo logfiles, and database control files. To use OMF, you must first configure the database to use OMF (see the “Configuring the Database to Use OMF” section). Once the database is configured for OMF, Oracle will create the datafiles required during the execution of a DDL statement such as create tablespace—if you do not specifically define the datafiles associated with that statement. OMF can be associated with tablespaces, temporary tablespace, redo logs, and control files in Oracle9i. Let’s look at some specifics of OMF with regards to the creation of tablespaces, redo logs, and control files.

Tablespace OMF You can create any tablespace using OMF, even the SYSTEM tablespace. To configure Oracle for this operation, you need to set the db_create_ file_destparameter in the database parameter file (see “Configuring the Database to Use OMF,” later in the chapter, for more on configuring OMF). For example, when you create a tablespace by issuing the create tablespace or create temporary tablespace commands without any datafile names, Oracle will create the needed datafile for that tablespace. Also, if you issue the create database command and do not provide a datafile name for the SYSTEM tablespace, then an OMF datafile will be created. Also, if you define a DEFULAT tablespace or an UNDO tablespace
in the create database command, then an OMF will be created for each of those tablespace types. The default size for any OMF is 100M, and the datafile(s) are set to autoextend with an unlimited maximum extent.

If you wish to define a file size other than 100M for a datafile, include the datafile keyword, and then include the size parameter (without a filename), and the datafile will be created at the requested size. You can also include autoextend off to disable the setting of autoextend on the OMF when it is created. An example of this is shown here:
CREATE TABLESPACE new_tbs DATAFILE SIZE 500M AUTOEXTEND OFF;