Introduction

“Choosing the right OODB architecture can mean orders of magnitude difference in performance and scalability characteristics rather than a few percentage points as found in relational implementations.”
To achieve maximum performance and scalability the most important thing is choosing the right application architecture. OODBs give applications much more direct access to the persistent data, so application architecture has much more impact on performance than is the case with an RDB. Or to put it another way, when using an
OODB the application architect has much more power to optimize performance than when using an RDB. Consequently the application architecture has more effect on performance and scalability than the choice of …show more content…

➢ Both of these two features can be used to group similar objects together, but it is normal for a system to support either classes or types and not both.

Overriding, Overloading and Late Binding

➢ Overloading: A class modifies an existing method, by using the same name, but with a different list, or type, of parameters.

➢ Overriding: The implementation of the operation will depend on the type of the object it is applied to.

➢ Late binding: The implementation code cannot be referenced until run-time.

Computational Completeness

SQL does not have the full power of a conventional programming language. Languages such as Pascal or C are said to be computationally complete because they can exploit the full capabilities of a computer. SQL is only relationally complete, that is, it has the full power of relational algebra. Whilst any SQL code could be rewritten as a C++ program, not all C++ programs could be rewritten in SQL.

For this reason most relational database applications involve the use of SQL embedded within a conventional programming language. The problem with this approach is that whilst SQL deals with sets of records, programming languages tend to work on a record at a time basis. This difficulty is known as the impedance mismatch. Object-oriented databases attempt to provide a seamless join between program and database and hence overcome the impedance mismatch. To make this possible the data manipulation language