Oracle CODASYL DBMS™

Enhancements to Oracle CODASYL DBMS continue to focus on high availability, performance, and very large database support – the very features that have given CODASYL DBMS a reputation for stability and reliability.

Oracle CODASYL DBMS

Oracle CODASYL DBMS is a multi-user, general purpose database management system that runs on the OpenVMS operating system. DBMS can be used to access and administer databases ranging in complexity from simple hierarchies to co mplex networks with multi-level relationships. It supports full concurrent access in a multi-user environment without compromising the integrity and security of the user's databases. The majority of DBMS installations occur through application providers using DBMS as the underlying database.

Oracle CODASYL DBMS is designed for users working in a structured application environment. The users are programmers, an alysts, designers, or administrators who use conventional planning and coding techniques to design, create, and maintain long-term applications for corporate use. The characteristics include high availability and throughput coupled with system manage ment features that minimize downtime. Examples are large-scale applications such as manufacturing and shop floor systems that require a stable environment not subject to change.

DBMS7: Strategic Enhancements

Strategic enhancements for Release 7 of DBMS included very large memory addressing support. Shared record cache allows DBMS to use as much physical memory as a computer system can support, so that frequently accessed records can be stored in memory to reduce disk I/O. Th e advantages include:

• reduced database page reads and writes;
• improved response time;
• much lower overhead to than accessing a page in a global or local buffer;
• shorter code path when a re cord is found in cache.

Hot Standby also provides disaster tolerance to DBMS users. This option prevents the DBMS database from becoming a single point of failure by physically duplicating the database at a geographically remote site. In the event of failure, the “hot standby” database becomes the master database and takes over application processing. Failure detection and failover can be achieved with minimal interruption to users and application processing. This option does not require specific hardware to operate, and no changes to the application code are needed.

DBMS7: Meeting Customer Requirements

As noted earlier, DBMS users need high availability and throughput coupled with system management features that minimize downtime. Another major enhancement supporting the demand for high availability is on-line restructuring of the database. Users are now permitted concurrent access to the database during a reload operation, thus reducing downtime to a minimum. The RELOAD operation can be stopped and restarted as necessary, and everything is journalled ensuring security.

Several other enhancements support ease of application maintenance and system management. These include additional application debugging aids, several new SHOW STATISTICS capabilities, documented fixed-format output of database parameters, and AIJ (after image journalling) backups in RMS or new tape format.

Future Paths

Oracle's strategy for CODASYL DBMS beyond Release 7 is continued emphasis on availability, VLDB capabilities, and performance. Possible features for the next release are: parallel reload enhancements, and improvements within the supporting environment to facilitate the use of SQL-based tools.

Product Roadmap

Our overall objective is that of continuous support and enhancement to ensure DBMS keeps its reputation for stability and quality.