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CHAPTER 18
Installation
IN THIS CHAPTER
- Oracle Software Options 418
- Installation Preparation 422
- Installing the Software 422
- Directory Structure 424
- Operating System Specifics 424
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In this chapter, you'll look at some of the issues involved in installing the Oracle software and database. Because Oracle runs on more than 90 different platforms, though, you'll just look at an overview of the process involved here. You can find the specifics for your operating system in the Oracle Installation and User 's Guide that comes with the software. In addition, you should study the last-minute System Release Bulletin that comes with the software, along with the even later produced README.DOC file located on the install media.
On most platforms, if a user process connects directly to the database server machine, you must know two things: the starting location of the Oracle software directory and the instance ID to which the user process will connect. This information is provided in different ways on various operating systems, but many use an operating system command file named something such as orauser or oraenv to set up these operating system variables as soon as a user logs on to a machine.
On most machines, during the installation process, you have the option to install a default database by choosing some menu options. Chapter 19, "Managing the Database," covers creating a database if you don't want to or cannot use the menus to give you this starting database. Usually, the menus are sufficient to create a practice database, but for production and real systems, you need more control over the choices available when creating a new database.
Installation of the Oracle tools usually is performed at the same time as installation of the Oracle software. For client/server environments, an added complication is that the tools exist on a different machine than that on which the database software resides. To enable the two machines to communicate between each other, you must install some networking software on both machines (such as TCP/IP). Also, on top of that, both machines need a flavor of SQL*Net installed so that the Oracle software can interface with the networking software. Installing SQL*Net software for the network protocol you're using generally is done at the same time as installing the Oracle server software and tools software.
This is one of the areas in which major differences exist among different operating systems because of the nature of the process.
Oracle Software Options
When you purchase the Oracle software, a number of additional software options are available. These options might not be available on all platforms at the same time, however. When the software is installed, you can decide which additional capabilities to install (described in the following sections).
Base Product Options
The standard product (without the addition of the Procedural, Distributed, Parallel, or other options) gives you the SQL language; without this, you can't do much on the database. In the near future, the PL/SQL language also will be included in the standard base product. In addition, the database locks only those rows that actually are being modified instead of locking out
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the entire table. (This was an option that had to be purchased separately in version 6 of the database server.)
The base product also includes the capability to perform parallel recoveries in cases of media failure, which means that you can have more than one process running the tablespace recover command. You can run all these processes in parallel, and they will use whichever archived and online redo log files are required for the tablespace being recovered. You also can issue parallel tablespace backup commands, as well as parallel loads of data from operating system files using the SQL*Loader product with the Direct Load Path option available with that product.
Procedural
The Procedural option gives you the capability to use PL/SQL and to create procedures, functions, packages, and database triggers. This option now is being bundled as part of the base product.
Distributed
The base product gives you the capability to write distributed queries (queries in the same transaction or even in the same statement to query tables on one or more databases), usually by using database links that already have been defined by the database administrator. In addition, the user can connect to a remote database and make changes to tables on that database.
One thing that is not possible without the Distributed option is the capability to make changes to tables on more than one database within the same transaction (the same commit unit). The Distributed option allows one transaction to make changes to more than one database. When the changes are committed (or rolled back), the Oracle server software ensures that either all the databases commit or, if anything goes wrong, that they all roll back the work. This feature is provided without requiring you to put in any more code than the normal commit or rollback statement.
The synchronization mechanism is provided using the two-phase commit algorithm, which synchronizes all the databases involved.
In addition, with the Distributed option, one non-Oracle database can take part in a distributed transaction. Usually this involves using the Oracle Gateway products, which allow access to non-Oracle data sources.
If any failures do occur with a distributed transaction, the Oracle RECO background process periodically tries to commit or roll back the changes on the databases involved. It is better for the database administrator to allow the RECO (Recoverer) process to recover the distributed transaction without getting involved. The Oracle data dictionary tables, DBA_ 2PC_NEIGHBORS and DBA_2PC_PENDING, give further information on the transactions involved in a distributed failure.
The Distributed option also is required if you want to create snapshotscopies of tables (usually) on other databases that are replicated automatically to your database at user-defined
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intervals. In addition, the Distributed option includes the capability to call procedures, functions, and packages that have been defined on remote databases. So, in theory (although not very practical), you can hold the database procedures, functions, and packages on one central database; all other databases can make calls to this central copy of the code.
Parallel Server
The Oracle Parallel Server option allows more than one instance to access the same set of database files. This option ensures, for example, that if a row is locked on one instance that it is reported as locked on any other instances accessing the same database.
You use the Parallel Server option when more than one processor is available (on the same machine or on different machines that are clustered together).
Parallel Query
The Parallel Query option improves performance of full-table scans . This allows a large query to be executed by multiple processes so that many processes can be used to perform parts of the query, with the results automatically merged together.
In addition, the Parallel Query option allows you to create indexes in parallel. This is similar in concept to the parallel query mentioned earlier, which you can use with more than one process to build different parts of the index. The results from each of these processes then are merged.
The Parallel Query option normally runs on machines on which more than one processor has been installed so that you can use the processing power of more than one processor to perform the heavy workloads you require.
Trusted Oracle Options
The Trusted Oracle option provides additional security than that available with the base product, and usually is found in military-type applications or those for which a high level of security is required. This gives you the ability to control which rows are accessible to which users, for examplesomething you can't easily do with the base product.
Text Server
The Text Server option of the database enables you to store, retrieve, and manage unstructured text. This option is useful in any situation in which a large amount of text or documents are to be processed and intelligently analyzed . The text and documents can be stored inside the Oracle database or outside on the machine's file system in one of the supported document types (for example, HTML, ASCII, Word, Acrobat, and so on).
The text is processed by using extensions to the SQL language. Text Server supports intelligent summaries of documents, fuzzy searches of text, proximity searches, and so on.
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