Types of Databases: Relational, Object-Oriented, Geographic and Distributed

Relational Databases (BDR)

Relational databases (BDR) are a collection of tables with unique names, which may be related to one or more other tables. Concepts such as referential integrity and primary keys ensure that a value referenced in one table is present in the table being referenced, and that a set of information can be represented consistently and accessed independently.

Object-Oriented Databases (BDOO)

Object-oriented databases (BDOO) have three main pillars: inheritance, polymorphism and encapsulation. This model offers greater flexibility in manipulation and a richer content structure, and objects can be handled consistently.

Conventional Databases vs. New Application Requirements

Conventional database systems feature uniformity among data items, record orientation, small data items, atomic fields, transaction management and static conceptual schemas.

New applications, however, require complex constraints, complex data structures, object identity and direct references, and application code that operates on internal data.

Objective and Definition

The objective of object-oriented databases is to model real-world objects in the most direct way possible. They combine an object-oriented programming language with a database management system.

Complex Objects

• Non-structured objects: require large volumes of storage, such as images or large text objects.
• Structured objects: built from components using the constructors available in the application.

Classes

Classes group objects that share the same structure and behavior. A class defines a set of attributes and methods.

Geographic Databases

Geographic databases store location-related information and provide efficient queries supported by indexes on spatial locations.

Geographic objects have conventional attributes, which describe their form, indicate their location on Earth, and indicate their validity.

Object View

• Reality is seen as a plane containing real objects.
• Entities are represented as points, lines and polygons.
• Each entity has a particular position, geometry and its own characteristics.

Conventional databases store alphanumeric attributes describing features.

Topology

Topology is a structure that stores spatial relationships between objects. In a topological database, the relationship between two objects is stored explicitly. Cartographic objects can be viewed and manipulated independently.

Raster Representation

The raster representation is characterized by a matrix of cells of regular size. Each cell has an associated set of values representing geographic features of the region. The position of a cell is determined by the row and column where it is located. Satellite images and digital elevation models are represented this way.

Vector Representation

The vector representation uses points, lines and polygons to represent geometric entities such as boundaries, which are drawn on the map. Streets, traffic networks and waterways are modeled this way.

Distributed Databases

A distributed database is a collection of different databases, logically interconnected through a computer network.

SGBDD and SBDD

A Distributed Database Management System (SGBDD) is a software system that manages the distributed database and makes the distribution transparent to the system or user. A Distributed Database System (SBDD) is the combination of the databases with the system.

What is not a Distributed Database?

A system that resides on a single node of the computer network is not a distributed database.

Main Characteristics of an SBDD

• Data is stored in various locations (or nodes).
• Processing occurs across interconnected nodes through a computer network.