Relational Database Management System Computer Science Essay

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A database is simply a collection of one or more relations or tables with columns and rows. The use of set theory allows for data to be structured in a series of tables that has both columns and rows. Each column corresponds to an attribute of that relation, while each row corresponds to a record that contains data values for an entity.

RDBMS refers to Relational Database Management System. RDBMS data is ordered in database tables, fields and records. Each RDBMS table contains a database table rows. Every database table contain one or more data table which is called data field.

In RDBMS data is stored into groups of tables, which must be related to some common fields (database table columns). RDBMS is also provided relational operators to control the data which are store into the database tables. Most RDBMS use SQL as database query language.

RDBMS is such a system which is simple, flexible, and productive. Because the tables are simple, data is easier to understand and communicate with others. RDBMS are flexible because users do not have to use predefined keys to input information. Also, RDBMS are more productive because SQL is easier to learn. This allows users to spend more time inputting instead of learning. More importantly, RDBMS's biggest advantage is the ease with which users can create and access data and extend it if needed. After the original database is created, new data categories can be added without the existing application being changed.

Limitation of RDBMS

There are limitations to the relational database management system. First, relational databases do not have enough storage area to handle data such as images, digital and audio/video. The system was originally created to handle the integration of media, traditional fielded data, and templates. Another limitation of the relational database is its inadequacy to operate with languages outside of SQL. After its original development, languages such as C++ and JavaScript were formed. However, relational databases do not work efficiently with these languages. A third limitation is the requirement that information must be in tables where relationships between entities are defined by values.

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Object Relational Database Management System (ORDBMS)

An object relational database is also called an object relational database management system (ORDBMS). This system simply puts an object oriented front end on a relational database (RDBMS). When applications interface to this type of database, it will normally interface as though the data is stored as objects. However the system will convert the object information into data tables with rows and columns and handle the data the same as a relational database. Likewise, when the data is retrieved, it must be reassembled from simple data into complex objects.

An object-relational database can be said to provide a middle ground between relational databases and object-oriented databases (OODBMS). In object-relational databases, the approach is essentially that of relational databases: the data resides in the database and is manipulated collectively with queries in a query language; at the other extreme are OODBMS in which the database is essentially a persistent object store for software written in an object-oriented programming language, with a programming API for storing and retrieving objects, and little or no specific support for querying.

Advantages of ORDBMS

Object Relational Database Management Systems gives the supporting capacity of massive storage, which is a very essential for web based system development.

It is very easy and quick to access the data in ORDBMS.

ORDBMS has such scalability which is large and robust.

ORDBMS possess tremendous manipulation power of object in a database.

ORDBMS supports object functionality by adding separate APIs and server subsystems

In ORDBMS it is very easy to redesign database and database engine is complete.

ORDBMS supports rich data types by adding a new object-oriented layer.

Apart from these advantages, an object relational database management system has some drawbacks. One of the major disadvantages is its incapability for high-speed internet applications. However, ORDBMSs are designed to manage large amounts of information, an important aspect in the development of website. The IDC opines that the ORDBMS market has the potential to surpass the size of ODBMS in the next couple of years in web based development.

Disadvantages of ORDBMS

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.

There are also those that believe that the RDMS is being extended for what will be a minority of applications that do not achieve optimal performance with current relational technology.

Instead of discussing object models, terms like 'user-defined data types' are used. The terminology of object-orientation abounds with terms like 'abstract types'. 'class hierarchies', and 'object models'. However, ORDBMSs vendors are attempting to portray object models as extensions to the relational model with some additional complexities.

This potentially misses the point of object-orientation, highlighting the large semantic gap between these two technologies.

Benefits of ORDBMS

The main benefit to this type of database lies in the fact that the software to convert the object data between a RDBMS format and object database format is provided. Therefore it is not necessary for programmers to write code to convert between the two formats and database access is easy from an object oriented computer language.

Limitation of ORDBMS

Complexity

Increased costs

Unclear if the ORDBMS will actually combine relationships and encapsulated objects to correctly and completely mirror the 'real world

Provision of a language(s)which will front end to SQL and will provide a migration path for existing SQL

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Object Oriented Database Management System (OODBMS)

Object-oriented database management system (OODBMS) the shorter form is ODBMS that stands for object database management system, which is also a database management system (DBMS) that offers the modelling and creation of data as objects. This contains some kind of maintain for classes of objects and the inheritance of class properties and methods by subclasses and their objects. There is presently no broadly agreed-upon standard for what constitute an OODBMS, and OODBMS products are considered to be still in their immaturity. In the intervening time, the object-relational database management system (ORDBMS), the idea that object-oriented database concepts can be apply to on relational databases, is more commonly encountered in available products. An object-oriented database interface standard is being developed by an industry group, the Object Data Management Group (ODMG). The Object Management Group (OMG) has already standardized an object-oriented data brokering interface between systems in a network.

http://upload.wikimedia.org/wikipedia/commons/thumb/5/5d/Object-Oriented_Model.jpg/320px-Object-Oriented_Model.jpg

Fig: object oriented database management model

Main Features of OODBMS

Complex objects: It deals with complex data and object which cannot deal other database management system.

Object Identity: It also can identify the data or object which is relevant or not.

Encapsulation: Data encapsulation is possible by OODBMS as a result it compact the large data into small data.

Classes: It defines class so that any complex data can be broken into classes.

Inheritance: Data inheritance is possible with OODBMS.

Overriding and late-binding: OODBMS offers data overriding and late binding and is a convenient way to classify data.

Extensibility: Data extensibility is the main feature of OODBMS

Computational completeness: The main beneficial side of OODBMS is computational completeness.

Persistence: By persistency it is possible to reserve data from the database.

Concurrency: Data concurrency is more flexible in OODBMS

Recovery: It is no harder job to recover lost data form database by using OODBMS.

Ad-hoc querying: OODBMS satisfy the Ad-hoc querying.

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http://www.odbms.org

Advantages of OODBMS

In RDBMS, there was enough wastage of time when objects had to be mapped with tables and vice versa. This is completely avoided with OODBMS. 

In OODBMS, data is described easily through class hierarchy. 

IN RDBMS, users have to face problems when identifying the records. They had to ensure that no two records had the same primary key. OODBMS completely avoids this aspect because of its unique OIDs.

Since interaction between objects and database is done transparently, there is no need for a query language to access data from an Object Oriented Database Management System. But one can still use queries in OODBMS. 

In OODBMS, a large class can hold several medium-sized classes, which can hold even more medium-sized classes. This means that OODBMs has the ability to handle complex data compared to RDBMS.

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Benefits of OODBMS

COMPLEX (INTER-) RELATIONSHIPS

If there are a lot of many-to-many relationships, tree structures or network (graph) structures then Versant's OODBMS solutions will handle those relationships much faster than a relational database.

COMPLEX DATA

For many applications, the most challenging aspect is controlling the inherent complexity of the subject matter itself - the complexity must be tamed. For these applications, a Versant OODBMS is the best answer. Architectures that mix technical needs such as persistence (and SQL) with the domain model are an invitation to disaster. Versant's OODBMS solutions let you develop using objects that need only contain the domain behaviour, freeing you from persistence concerns.

NO MAPPING LAYER

It is difficult, time consuming, expensive in development, and expensive at run time, to map the objects into a relational database and performance can suffer. Versant's OODBMS solutions store objects as objects - yes, it's as easy as 1, 2, 3. Versant's object database solutions are designed to store many-to-many, tree and network relationships as named bi-directional associations without having the need for JOIN tables. Hence, Versant's object database solutions save programming time, and objects can be stored and retrieved faster. Modern O/R mapping tools may simplify many mapping problems, however they don't provide seamless data distribution or the performance of Versant's OODBMS solutions.

FAST AND EASY DEVELOPEMENT, ABILITY TO COPE WITH CONTINOUS EVOLUTION

The complexity of telecommunications infrastructure, transportation networks, simulations, financial instruments and other domains must be tamed. Architectures that mix technical needs such as persistence (and SQL) with the domain model are an invitation to disaster. Versant's OODBMS solutions let you develop using objects that need only contain the domain behaviour, freeing you from persistence concerns.

http://www.versant.com

Disadvantages of OODBMS

Lack of a universal data model

Ad-hoc querying compromises encapsulation.

Locking at object-level impacts performance

Complexity

Lack of support for views

Lack of support for security

Comparison of RDBMS, OODBMS and ORDBMS:

Characteristics

RDBMS

ODBMS

ORDBMS

Standard Definition

SQL2

ODMG-2.0

SQL3 (in process)

Supportive object oriented features

Not supportive in RDBMS; It is not easy to map the database with program object.

Extensively supported

Allow only inadequate support; The new data types mostly

Handling

It is uncomplicated to use

It is well basically for the programmers; End user can have access to the SQL.

It is easy to use except some extension.

Complex relationships supportive

Abstract data types is not supported

Complex data type with inter relationships and other complex data type is supported.

Abstract data types and complex relationships are supported here.

Performance

Performance is very good

Performance is comparably less.

Performance is very well

Product maturity

Comparatively older and it is very mature.

Relatively this concept is older and mature.

It is immature as it is still in development stage.

SQL usability

Features of Structured Query Language are extensively supported.

SQL and OQL are mostly similar, with some additional features such as Complex objects and object oriented features.

SQL3 is incorporated with it, which is being developed with Object Oriented characteristics.

Advantages

Structured Query Language dependant, query optimization is relatively simple hence it has good performance.

Complex applications can be handled easily, also code reusability is possible so need less coding.

Large and complex application can be handled easily. Also complex query application is possible.

Disadvantages

Not able to handle complex applications

Performance is low due to complex query optimization, Not able to support large-scale systems

In case of web application performance is Low.

Support from vendors

The market size is very large as it is well thought-out to be highly doing well. But unfortunately now a day, merchants are having more interest towards ORDBMS.

Due to present vast market of RDBMS, it is continuously lacking vendor support.

It has very good future as all vendors are moving towards RDBMS leaving all other DBMS system.

Source: International Data Corporation, 1997 available on http://lankaforum.net/english/doc/tutorials/comparisonofrdbmsoodbmsordbms.php

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