Object-oriented query languages: the notion and the issues

Achievements and Weaknesses of Object-Oriented Databases.

“…Therefore, two objects are different if they have different OIDs, even if they have the same structures and the same values for all their properties. In the RDB model, where object identification is supported by user-defined keys, those objects would be considered the same object [8].…”

“…Properties too can have complex structures, and can be defined using the collection constructor. Furthermore, they can have nonprimitive objects as values, allowing deeply nested object structures [8].…”

“…Overriding is the substitution of the property domain with a new domain or the substitution of a method implementation with a different one [8].…”

“…Attempts to use relational database technology for advanced applications like computer aided design (CAD), computer aided manufacturing (CAM), software engineering, knowledge-based systems, and multimedia systems, quickly exposed the shortcomings of relational database systems [22], [8]. The need to perform complex manipulations on existing databases and a new generation of database applications generated a need that would be better satisfied by object-oriented databases (OODBs).…”

Semantic query optimization for methods in object-oriented database systems

“…For instance, by lifting tuple constructors and selectors in this way, the standard relational operators of Cartesian product and projection can be expressed. In fact it was shown that together with set collapse which is defined as g(S) := ƒs Ů S, where S is of type {{T}}, this operator can serve as the basis for a complete complex object algebra [6]. Example 6: The usual projection operator p a on a relation R can be expressed as follows p a (R) := m< lx.…”