Database management system (DBMS): classification, definition and functions

Data is always structure and content, syntax and semantics. In the context of database tables, relationship between tables, queries and their results. Not to say that the dominant idea of relational databases - ideal, but practical, comfortable and allows to describe any scope.

If the database is a collection of tables, the database management system (DBMS) is to support several databases and giving each of them proper functionality in terms of administration, work and reading. Over time, database found a lot of very specific functions that are considered to be the de facto standard, and received its own description language, the work and sampling.

Basic DBMS functionality

Databases allow us to represent the data set through the system tables, specify relationships between tables, define queries, and form of desired results, and provide two options:

• Change;
• Read only.

Actually, from the DBMS more is required, you need to provide access code for the purposes of administration or operation (change or read). The user has direct access to the data, but after a certain code available to him a wide spectrum of functions implemented by the DBMS.

The Format, Protocol and General algorithm using a database always known, although the current classification system DBMS demonstrates the great diversity of concepts and options for implementation.

Concept systems data management

The Basic concept, which, of course, leads from the moment of birth and perfected to this day, represents the Foundation of the design of database management systems - relational model. A database is a set of tables and relationships between them. So it was, is, but it's still not too long.

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The Rest of the data model:

• Hierarchical;
• Network;
• ER-model (entity - relationship);
• Object-oriented;
• Object-relational, etc.

They have their niche but in each of them the fundamentals are all the same relational model. In fact, different concepts of data organized in a data system, no doubt, and obviously only one thing: all the data always makes sense.

How to reflect the meaning in formal computer database model? Judging by the few names of the models in the database, a special problem here, but still “pure relational model" of the find the most that neither is practical application: how to call a solved problem processing what adjective to attach to the name of its database - it doesn't matter, it is important that the problem is solved.

Classification of systems data management

The Most basic category, which has important practical significance: the applicability of the system to solve the problem. Here you can all DBMS fall into four main groups:

• The data model;
• Distribution;
• Methods of access
• Flexibility.

This is a General classification of modern DBMS.

The Concept of distribution is important, although from a semantic point of view, no matter how distributed database, it is important that it is the correct version of access.

Methods access to data is also important: a site may require. from the database managed by Oracle, but getting/writing here will be not so constructed, as when using MySQL.

Flexibility - the criterion is relative, but in most cases it should be considered. Not every project requires a dynamics and ensure a high level of security access, secure storage and so Many tasks need to be developed accordingly to the application. Selecting a database with limited functionality can lead in the future to unnecessary spending on replacement system which has limited capabilities.

DBMS Functionality

Following tradition, the classification and the functions of the database play a significant role in the development of technical specifications or it project involving large amounts of data. The term “large” may mean specific level of this (image processing) or number of records (text processing).

The functionality of the tasks and expected solutions may exhibit distinct requirements. In particular, the choice of DBMS (classification data):

• Presentation of data (video, audio, text, different combinations);
• Structure/formalisation (structured, unstructured);
• Character/source (hierarchical, relational, network);
• Format and storage location (local, distributed);
• Users (one, many).

This issue affects only part of the highlights for the preference of one DBMS to another. There are many applications where the choice of DBMS classification by any criterion is irrelevant. For example, the choice of content management system for the development of the site will put the developer in front of an unambiguous selection of only one specific database.

Large databases and complex connect

Modern information DBMS level (classification according to importance and responsibilities):

• Terabytes of information (a single large file, many small files);
• Megabytes (multiple files describing a single database and the data contained therein).

But the significance and the responsibility is always great not only in the first case. There are many important projects, when there are small amounts of information contribute to the decision-taking.

Usually the first criterion defines as the absolute leader of the Oracle, second MySQL. They have a lot in common, but there are many fundamental differences. When there is a task to connect the web resource to the Oracle database without the use of her own instruments and technologies, many questions arise. Complex connect - not a rarity, and often a simple condition for achieving a solution.

No less number of problems with the delivery of the data occurs at their location in a LAN server MS SQL Server to which a connection is available through several hardware routers.

In fact, in actual practice, all important components: architecture of DBMS, classification of DBMS functionality, variability of the connectivity and bandwidth of communication channels.

Access Security and data storage

Knowledge of DBMS, classification, theory of databases in General, practical experience and other conceptual issues undoubtedly are important. The reliability of the hardware component is very high today, but the question of code quality, and especially its semantics, relevant to this day.

To Provide secure access to the database all DBMS, but what about the common practice of copying databases to backup?

This flawed idea characteristic of the database, located in one file or in multiple files. In the first case, the loss of a single byte or bit will ruin the whole file, and in the second case a shallow copy of the description of a database or files containing the data will lead to unpredictable consequences.

Strangely, the developers of the DBMS is not concerned about these facts, but if they have taken the necessary steps and closed once and for all the question of data availability outside of the system controls them, then there'd be the dilemma for DBMS classification is simplified to a limit:

• Makes sense to use (safe, secure, always available);
• Can't be used (all controlled by the DBMS vendor).

It is Impossible to control everything, the more experienced the programmer, the more options it leaves to the customer. Close data for external control and changes - so ensure the problem is not solved for a long life.

The Issue of security and availability of data lies beyond any solution. It belongs to the company infrastructure, local area networks, perimeter security, etc.

By itself, data, databases and their management should be as open and accessible while respecting the established, tested by long practice and natural rules requirements.

The Social aspect of the DBMS

Considering the different ways of classifying a DBMS, you should pay special attention to the social component in the context of the theory and its applicability in practice.

When there was a LAN and the database is on the server, and DBMS gave access to many users, it was only just: the architecture of the file server is very practical, today is:

• File server;
• Client-server;
• Built-in database.

Three sides of the same coin. No matter where the database itself, not matter what the chosen DBMS. It is important that the data and code using them should be as mobile and accessible, but to be within the perimeter of the total safety under the watchful protection not only from technological factors (attacks, threats, destructive interference), but also from the behavioral point in the sense of employees developing code or using the data.