Object-RelationalDBMSs.ppt

Object-Relational DBMSs By Yao-Wen Tu CS157b 12/09/2003 Prof. Sin-Min Lee Introduction to Object-Relational DBMSs Several major software companies including IBM, Informix, Microsoft, Oracle, and Sybase have all released object-relational versions of their products. These companies are promoting a new, extended version of relational database technology called object-relational database management systems also known as ORDBMSs. Introduction to Object-Relational DBMSs (Cont) This article compares and contrasts this new class of database with the relational databases, RDBMS from which they are evolving and also with efficient object-oriented databases, OODBMSs, also known as object databases, ODBMSs. Does a database supporting complex applications have to be object-oriented? A certain group thinks that future applications can only be implemented with pure object-oriented systems. Initially these systems looked promising. However, they have been unable to live up to the expectations. A new technology has evolved in which relational and object-oriented concepts have been combined or merged. These systems are called object-relational database systems. The main advantages of ORDBMSs are massive scalability and support for object-oriented features. Advantages of ORDBMSs The main advantages of extending the relational data model come from reuse and sharing. Reuse comes from the ability to extend the DBMS server to perform standard functionality centrally, rather than have it coded in each application. If we can embed the functionality in the server, it saves having to define it in each application that needs it, and consequently allows the functionality to be shared by all applications. Disadvantages of ORDBMSs The ORDBMSs approach has the obvious disadvantage of complexity and associated increased costs. There are proponents of the relational approach that believe the essential simplicity and purity of the relational model are lost with these types of extension. Ther