In an earlier article, we covered some of the new data warehouse characteristics of Oracle 9i and discussed a few of the version’s changes. Continuing with our overview, we’ll turn our attention now to the database, availability, and WebServer enhancements in Oracle 9i.
Improved systems management
Oracle has been struggling for many years to make it easy for database administrators to configure a complex Oracle environment. At the lowest level, all of the Oracle configuration information exists inside flat files, and it is the responsibility of the Oracle DBA to know where these files are and to understand the internal meaning of thousands of database parameters.
Oracle has attempted to get around this cumbersome aspect of database management by creating wizard-based tools that will automatically generate the configuration syntax and write them to the database configuration files. In Oracle8, these wizard tools are quite clumsy and often make errors, but in Oracle9i, the tools are significantly improved.
Oracle is also beginning to step out of its traditional database-only monitoring with products that actually monitor the relative CPU load of different servers in an extended WebServer environment. Oracle promises to provide tools that will monitor disk space in memory usage on Oracle servers. This is a rather surprising move for Oracle, which previously limited its monitoring to the activity within the database management system itself. With this new Oracle9i feature, Oracle is competing with third-party server monitoring vendors such as BMC Software and Tivoli.
One of the most exciting features of Oracle9i is the improved memory management that allows Oracle's system global area (SGA) to be resized. Prior to Oracle9i, database administrators had to define the RAM and memory regions for the SGA (via the init.ora parameter file), and they had no control over resizing those memory regions without shutting down and restarting the Oracle database.
In Oracle9i, the database administrator can dynamically alter the SGA and remove space from all of the major areas of the SGA, including the database buffers, the shared pool, and other integral components of an Oracle database. For example, if the DBA detects that the shared pool is short on storage, he or she will be able to dynamically remove space from the database block buffers and reallocate them to the shared pool.
This ability to dynamically change the SGA will dramatically increase the availability of 24/7 Oracle systems and make it far easier to keep Oracle databases running continuously for long periods of time.
In another interesting turn of events, Oracle9i now promises database recovery directly from the online redo logs. Oracle redo logs contain the “after” images of all changed rows in the Oracle database and are used to roll-forward the database in cases of disk failure. Prior to Oracle9i, Oracle expressly refused to support software that read information from the online redo logs. But now, Oracle allows this information to be read directly from the online redo logs, which will greatly improve the performance and maintenance of 24/7 online Oracle database systems. For example, by allowing reads from the online redo logs, an existing database can be cloned and restarted while remaining synchronized with the original database.
High availability enhancements
To enhance its features for handling high availability needs, Oracle has implemented a standard technique used by Oracle DBAs for many years. When systems require continuous availability, the Oracle database administrator makes a copy of the Oracle database and keeps it in recovery mode. For archive purposes, redo log files are generated from the primary database and then transferred to the other database server and fed into the recovering database. This effectively keeps the standby database very close to the production database in terms of the currency of the data.
Oracle has incorporated this common DBA trick into the base product within Oracle9i as a new tool called the Data Guard Broker. The tool is designed to manage all of the activities of a primary and standby database and to make the operational application of the redo logs more transparent to the system.
With Oracle commitment to Web-based access, Oracle is now offering some new tools for monitoring and managing the WebServer environment.
Web site statistics
Oracle has implemented WebServer statistics with Oracle Clickstream Intelligence. Clickstream collects Web access data for Web site traffic analysis, customer profiling, and real-time recommendations. This is similar to ordinary WebServer statistics where the administrator can view the number of hits for each Web page, the access patterns by hour of the day and day of the week, and the specific access paths for individual users. Clickstream technology enables Oracle9i to offer customized recommendations.
Oracle has greatly improved its WebServer software by adding the Oracle9i database appliance. This database appliance communicates closely with the WebServer software, allowing multiple Web servers to balance the load of connections to the Oracle databases. Oracle9i makes it easier for Web developers to balance the load between multiple Web servers in many e-commerce environments.
It’s vital to separate the hype from the facts of any Oracle release. Oracle, just like all software vendors, glamorizes their new features and engages in lavish advertising campaigns. But all hype aside, Oracle9i has some very useful new features and tools that will help Oracle keep its position as the world’s most popular database.