In Chapters 25 to 27 we examined some of the background concepts of object-orientation
and Object-Oriented Database Management Systems (OODBMSs). In Chapter 25 we also
looked at the types of advanced database application that are emerging and the weaknesses
of current RDBMSs that make them unsuitable for these types of application. InChapters 26 and 27 we discussed the OODBMS in detail and the mechanisms that make
it more suitable for these advanced applications. In response to the weaknesses of relational
systems, and in defense of the potential threat posed by the rise of the OODBMS,
the RDBMS community has extended the RDBMS with object-oriented features, giving
rise to the Object-Relational DBMS (ORDBMS). In this chapter we examine some of
these extensions and how they help overcome many of the weaknesses cited in Section
25.2. We also examine some of the problems that are introduced by these new extensions
in overcoming the weaknesses.