Introducing Oracle, Page 5
Oracle includes many features that make the database easier to manage. We've divided the discussion in this section into four categories: Oracle Enterprise Manager, add-on packs, backup and recovery, and database availability.
Oracle Enterprise Manager
As part of every Database Server, Oracle provides the Oracle Enterprise Manager (EM), a database management tool framework with a graphical interface used to manage database users, instances, and features (such as replication) that can provide additional information about the Oracle environment. EM can also manage Oracle9iAS and Oracle iFS, Internet Directory, and Express.
Several optional add-on packs are available for Oracle, as described in the following sections and in more detail in Chapter 5. In addition to these database-management packs, management packs are available for Oracle Applications and for SAP R/3.
Standard Management Pack
The Standard Management Pack for Oracle provides tools for the management of small Oracle databases (e.g., Oracle Server/Standard Edition). Features include support for performance monitoring of database contention, I/O, load, memory use and instance metrics, session analysis, index tuning, and change investigation and tracking.
You can use the Diagnostics Pack to monitor, diagnose, and maintain the health of Enterprise Edition databases, operating systems, and applications. With both historical and real-time analysis, you can automatically avoid problems before they occur. The pack also provides capacity planning features that help you plan and track future system-resource requirements.
With the Tuning Pack, you can optimize system performance by identifying and tuning Enterprise Edition database and application bottlenecks such as inefficient SQL, poor data design, and the improper use of system resources. The pack can proactively discover tuning opportunities and automatically generate the analysis and required changes to tune the system.
Change Management Pack
The Change Management Pack helps eliminate errors and loss of data when upgrading Enterprise Edition databases to support new applications. It can analyze the impact and complex dependencies associated with application changes and automatically perform database upgrades. Users can initiate changes with easy-to-use wizards that teach the systematic steps necessary to upgrade.
Oracle Enterprise Manager can be used for managing Oracle Standard Edition and/or Enterprise Edition. Additional functionality for diagnostics, tuning, and change management of Standard Edition instances is provided by the Standard Management Pack. For Enterprise Edition, such additional functionality is provided by separate Diagnostics, Tuning, and Change Management Packs.
Backup and Recovery
As every database administrator knows, backing up a database is a rather mundane but necessary task. An improper backup makes recovery difficult, if not impossible. Unfortunately, people often realize the extreme importance of this everyday task only when it is too late--usually after losing business-critical data due to a failure of a related system.
The following sections describe some products and techniques for performing database backup operations. We discuss backup and recovery strategies and options in much greater detail in Chapter 10.
Typical backups include complete database backups (the most common type), tablespace backups, datafile backups, control file backups, and archivelog backups. Oracle8 introduced the Recovery Manager (RMAN) for the server-managed backup and recovery of the database. Previously, Oracle's Enterprise Backup Utility (EBU) provided a similar solution on some platforms. However, RMAN, with its Recovery Catalog stored in an Oracle database, provides a much more complete solution. RMAN can automatically locate, back up, restore, and recover datafiles, control files, and archived redo logs. RMAN for Oracle9i can restart backups and restores and implement recovery window policies when backups expire. The Oracle Enterprise Manager Backup Manager provides a GUI-based interface to RMAN.
Incremental backup and recovery
RMAN can perform incremental backups of Enterprise Edition databases. Incremental backups back up only the blocks modified since the last backup of a datafile, tablespace, or database; thus, they're smaller and faster than complete backups. RMAN can also perform point-in-time recovery, which allows the recovery of data until just prior to a undesirable event (such as the mistaken dropping of a table).
Legato Storage Manager
Various media-management software vendors support RMAN. Oracle bundles Legato Storage Manager with Oracle to provide media-management services, including the tracking of tape volumes, for up to four devices. RMAN interfaces automatically with the media-management software to request the mounting of tapes as needed for backup and recovery operations.
While basic recovery facilities are available for both Oracle Standard Edition and Enterprise Edition, incremental backups have typically been limited to Enterprise Edition.
Database availability depends upon the reliability and management of the database, the underlying operating system, and the specific hardware components of the system. Oracle has improved availability by reducing backup and recovery times. It has done this through:
- Providing online and parallel backup and recovery
- Improving the management of online data through range partitioning
- Leveraging hardware capabilities for improved monitoring and failover
The relevant features are described in the following sections.
Oracle introduced partitioning as an option to Oracle8 to provide a higher degree of manageability and availability. You can take individual partitions offline for maintenance while other partitions remain available for user access. In data warehousing implementations, partitioning is frequently used to implement rolling windows based on date ranges. Hash partitioning, in which the data partitions are divided up as a result of a hashing function, was added to Oracle8i to enable an even distribution of data. You can also use composite partitioning to enable hash subpartitioning within specific range partitions. Oracle9i adds list partitioning, which enables the partitioning of data based on discrete values such as geography.
Oracle9i Data Guard
Oracle first introduced a standby database feature in Oracle 7.3. The standby database provides a copy of the production database to be used if the primary database is lost--for example, in the event of primary site failure, or during routine maintenance. Primary and standby databases may be geographically separated. The standby database is created from a copy of the production database and updated through the application of archived redo logs generated by the production database. The Oracle9i Data Guard product fully automates this process; previously, you had to manually copy and apply the logs. Agents are deployed on both the production and standby database, and a Data Guard Broker coordinates commands. A single Data Guard command is used to run the eight steps required for failover.
In addition to providing physical standby database support, Oracle9i Data Guard (second release) will be able to create a logical standby database. In this scenario, Oracle archive logs are transformed into SQL transactions and applied to an open standby database.
Failover features and options
The failover feature provides a higher level of reliability for an Oracle database. Failover is implemented through a second system or node that provides access to data residing on a shared disk when the first system or node fails. Oracle Fail Safe for Windows NT/2000, in combination with Microsoft Cluster Services, provides a failover solution in the event of a system failure. Unix systems such as HP-UX and Solaris have long provided similar functionality for their clusters.
Oracle Parallel Server/Real Application Clusters failover features
The Oracle Parallel Server (OPS) option, renamed Real Application Clusters in Oracle9i, can provide failover support as well as increased scalability on Unix and Windows NT clusters. Oracle8i greatly improved scalability for read/write applications through the introduction of Cache Fusion. Oracle9i improved Cache Fusion for write/write applications by further minimizing much of the disk write activity used to control data locking.
With Real Application Clusters, you can run multiple Oracle instances on systems in a shared disk cluster configuration or on multiple nodes of a Massively Parallel Processor (MPP) configuration. The Real Application Cluster coordinates traffic among the systems or nodes, allowing the instances to function as a single database. As a result, the database can scale across hundreds of nodes. Since the cluster provides a means by which multiple instances can access the same data, the failure of a single instance will not cause extensive delays while the system recovers; you can simply redirect users to another instance that's still operating. You can write applications with the Oracle Call Interface (OCI) to provide failover to a second instance transparently to the user.
Parallel Fail Safe/RACGuard
Parallel Fail Safe, renamed RACGuard in Oracle9i, provides automated failover with bounded recovery time in conjunction with Oracle Parallel Server/Real Application Clusters. In addition, Parallel Fail Safe provides client rerouting from the failed instance to the instance that is available with fast reconnect and automatically captures diagnostic data.
Advanced high-availability features such as the Partitioning option and Real Application Clusters have typically been available for Oracle Enterprise Edition but not for Standard Edition.
Many Oracle tools are available to developers to help them present data and build more sophisticated Oracle database applications. Although this book focuses on the Oracle database, this section briefly describes the main Oracle tools for application development: Oracle Forms Developer, Oracle Reports Developer, Oracle Designer, Oracle JDeveloper, Oracle Discoverer Administrative Edition, and Oracle Portal.
Oracle Forms Developer
Oracle Forms Developer provides a powerful tool for building forms-based applications and charts for deployment as traditional client/server applications or as three-tier browser-based applications via Oracle9i Application Server. Developer is a fourth-generation language (4GL). With a 4GL, you define applications by defining values for properties, rather than by writing procedural code. Developer supports a wide variety of clients, including traditional client/server PCs and Java-based clients. Version 6 of Developer adds more options for creating easier-to-use applications, including support for animated controls in user dialogs and enhanced user controls. The Forms Builder in Version 6 includes a built-in JVM for previewing web applications.
Oracle Reports Developer
Oracle Reports Developer provides a development and deployment environment for rapidly building and publishing web-based reports via Reports for Oracle9i Application Server. Data can be formatted in tables, matrices, group reports, graphs, and combinations. High-quality presentation is possible using the HTML extension Cascading Style Sheets (CSS).
Oracle JDeveloper was introduced by Oracle in 1998 to develop basic Java applications without writing code. JDeveloper includes a Data Form wizard, a BeansExpress wizard for creating JavaBeans and BeanInfo classes, and a Deployment wizard. JDeveloper includes database development features such as various Oracle drivers, a Connection Editor to hide the JDBC API complexity, database components to bind visual controls, and a SQLJ precompiler for embedding SQL in Java code, which you can then use with Oracle. You can also deploy applications developed with JDeveloper using the Oracle9i Application Server. Although JDeveloper uses wizards to allow programmers to create Java objects without writing code, the end result is generated Java code. This Java implementation makes the code highly flexible, but it is typically a less productive development environment than a true 4GL.
Oracle Designer provides a graphical interface for Rapid Application Development (RAD) for the entire database development process--from building the business model to schema design, generation, and deployment. Designs and changes are stored in a multiuser repository. The tool can reverse-engineer existing tables and database schemas for reuse and redesign from Oracle and non-Oracle relational databases.
Designer also includes generators for creating applications for Oracle Developer, HTML clients using Oracle9i Application Server, and C++. Designer can generate applications and reverse-engineer existing applications or applications that have been modified by developers. This capability enables a process called round-trip engineering, in which a developer uses Designer to generate an application, modifies the generated application, and reverse-engineers the changes back into the Designer repository.
Oracle Discoverer Administration Edition
Oracle Discoverer Administration Edition enables administrators to set up and maintain the Discoverer End User Layer (EUL). The purpose of this layer is to shield business analysts using Discoverer as an ad hoc query or ROLAP tool from SQL complexity. Wizards guide the administrator through the process of building the EUL. In addition, administrators can put limits on resources available to analysts monitored by the Discoverer query governor.
Oracle9iAS Portal, introduced as WebDB in 1999, provides an HTML-based tool for developing web-enabled applications and content-driven web sites. Portal application systems are developed and deployed in a simple browser environment. Portal includes wizards for developing application components incorporating "servlets" and access to other HTTP web sites. For example, Oracle Reports and Discoverer may be accessed as servlets. Portals can be designed to be user-customizable. They are deployed to the middle-tier Oracle9i Application Server.
The main enhancement that Oracle9iAS Portal brings to WebDB is the ability to create and use portlets, which allow a single web page to be divided up into different areas that can independently display information and interact with the user.
All of these pieces are bundled in the Internet Developer Suite. The Internet Developer Suite is an option.
Oracle Lite is Oracle's suite of products for enabling mobile use of database-centric applications. Key components of Oracle Lite include the Oracle Lite database and iConnect, which consists of Advanced Replication, Oracle Mobile Agents (OMA), Oracle Lite Consolidator for Palm, and Oracle AQ Lite.
Although the Oracle Lite database engine can operate with much less memory than other Oracle implementations (it requires less than 1 MB of memory to run on a laptop), Oracle SQL, C and C++, and Java-based applications can run against the database. Java support includes support of Java stored procedures, JDBC, and SQLJ. The database is self-tuning and self-administering. In addition to Windows-based laptops, Oracle Lite is also supported on handheld devices running WindowsCE and Palm OS.
A variety of replication possibilities exist between Oracle and Oracle Lite, including the following:
- Connection-based replication via Oracle Net, Net8, or SQL*Net synchronous connections
- Wireless replication through the use of Advanced Queuing Lite, which provides a messaging service compatible with Oracle Advanced Queuing (and replaces the Oracle Mobile Agents capability available in previous versions of Oracle Lite)
- File-based replication via standards such as FTP and MAPI
- Internet replication via HTTP or MIME
You can define replication of subsets of data via SQL statements. Because data distributed to multiple locations can lead to conflicts--such as which location now has the "true" version of the data--multiple conflict and resolution algorithms are provided. Alternatively, you can write your own algorithm.
In typical usage of Oracle Lite, the user will link her handheld or mobile device running Oracle Lite to an Oracle Database Server. Data and applications will be synchronized between the two systems. The user will then remove the link and work in disconnected mode. After she has performed her tasks, she'll relink and resynchronize the data with the Oracle Database Server.
About the Authors
Rick Greenwald has been active in the world of computer software for nearly two decades, including stints with Data General, Cognos, and Gupta. He is currently an analyst with Oracle Corporation. He has been a principal author of ten books and countless articles on a variety of technical topics, and has spoken at conferences and training sessions across six continents. In addition to Oracle in a Nutshell, Rick's books include Oracle Essentials: Oracle9i, Oracle8i, and Oracle8 (principal author with Robert Stackowiak and Jonathan Stern, O'Reilly & Associates, 2001), Oracle Power Objects Developer's Guide (principal author with Kasu Sista and Richard Finklestein, Oracle Press, 1995); Mastering Oracle Power Objects (principal author with Robert Hoskins, O'Reilly & Associates, 1996); Using Oracle Web Server (principal author with many others, Que Publishing, 1997); The Oracle WebDB Bible (principal author with Jim Milbery, IDG Books Worldwide, 1999); and Administering Exchange Server (principal author with Walter Glenn, Microsoft Press, 1999).
Robert Stackowiak has worked for 20 years in IT industry related roles that have included software development, management of software development, systems engineering, sales and sales consulting, and business development. He currently is recognized worldwide as a field sales expert in data warehousing at Oracle, and previously was well recognized for his work at IBM's RISC System/6000 Division, Harris Computer Systems, and the U.S. Army Corps of Engineers. Bob has spoken at numerous computer related conferences and has conducted briefings with companies based around the world. His papers regarding data warehousing and computer and software technology have appeared in publications such as The Data Warehousing Institute's Journal of Data Warehousing, Informix Tech Notes, and AIXcellence Magazine. Robert's books include Oracle Power Objects Developer's Guide, principal author with Kasu Sista and Richard Finklestein (Oracle Press, 1995); Mastering Oracle Power Objects, principal author with Robert Hoskins (O'Reilly & Associates, 1996); Special Edition: Using Oracle Web Server, principal author with many others (Que Publishing, 1997); The Oracle WebDB Bible, principal author with Jim Milbery (IDG Books Worldwide, 1999); and Administering Exchange Server, principal author with Walter Glenn (1999)
Jonathan Stern has over 11 years of IT experience, including senior positions in consulting, systems architecture, and technical sales. He has in-depth experience with the Oracle RDBMS across all major open systems hardware and operating systems, covering tuning, scaling and parallelism, Parallel Server, high availability, data warehousing, OLTP, object-relational databases, N-tier architectures, and emerging trends such as Java and CORBA. He is the Central USA Technical Team Leader at Ariba, Inc., the leading vendor of electronic commerce solutions for strategic procurement. Previously, he led a team of highly experienced database specialists at Oracle Corporation providing technical depth and strategic assistance to Oracle's largest customers in the North Central USA. Jonathan has authored papers and presented at internal and external conferences on topics such as scaling with Oracle's dynamic parallelism and the role of reorganizing segments in an Oracle database.
Source of this material
|This is Chapter 1: Introducing Oracle from the book Oracle Essentials : Oracle9i, Oracle8i & Oracle8 (2nd Edition) (ISBN:0-596-00179-7) written by Rick Greenwald, Robert Stackowiak & Jonathan Stern, published by O'Reilly & Associates. |
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