Overview of Database Management Systems

All human activity is inextricably linked with a variety of information catalogs and databases. The library registry, address book, addresses in a mobile phone or tablet - this is far from a complete list of structured information that we use. But computers like precision, so let's define.

So, the database (DB) is a set of logically interconnected data describing the information state of objects in various subject areas and processed by computer equipment.

The database management system is a software and language environment for creating, managing and processing information databases. Assignment of DBMS:

• Work with databases on the external (disks, tapes, etc.) and RAM;
• Shared user access;
• Control changes, archiving and restoring databases;
• The provision of an access language for processing information ;
• Utility for creating, modifying and managing databases.

In simpler terms, the database defines the method of storing information , and the DBMS provides the means for its processing . In addition, the database management systems are divided into general application systems that can process various data and specialized data, developed for a specific subject area or type of information. An example of specialized database management systems are object-oriented.

Relational management systems

Since the advent of computer databases, many models of their work have been created, but the relational model has proved to be the most universal. It is a linked set of information tables, guarantees the integrity and minimal redundancy of information. The table model turned out to be applicable to most subject areas, and the market of relational database management systems began to develop at a rapid pace. The figure shows an example of the relational structure "Student base".

All relational DBMSs support the ANSI standard of SQL language and the basic principles of the relational model, which ensures the operation of applications on different DBMSs. Additionally, large DBMSs have their own additions to the SQL extension. Examples of a database management system for large projects are Microsoft SQL Server and Oracle.

The relational model is also successfully used in the development of Internet projects. Examples are MySQL and PostgreSQL.

NoSQL technology

The increase in the volume of information and the complication of the interconnections led to the emergence of new database management systems. Information ceased to be independent of each other, and sometimes it is impossible to describe its structure rigidly. Relational databases can no longer cope with such tasks. This led to the emergence of a new type of information bases and management systems, which received the general name NoSQL ("no SQL").

The main categories of NoSQL databases are:

1. "Key-Value" . The most popular DBMSs are Redis, Voldemort, Tokyo Cabinet and Dynomite.
2. Clones of BigTable. Developed by Google for internal use in the search engine. Officially BigTable Is not offered, but there is a DBMS based on it. This is Hadoop, Hypertable and Cassandra.
3. Document-oriented. The most popular are Berkeley DB XML, MongoD, eXist and CouchDB.
4. Base on the theory of graphs. Used in Neo4j, Sones graphDB and AllegroGraph.

The future of the DBMS

The market for database management systems continues to evolve and is increasingly inclined to use NoSQL solutions. Of course, on the "classic" SQL implemented a huge number of software systems of varying complexity, and behind it are such giants of the market as Microsoft and Oracle. But with a high degree of certainty, it can be assumed that NoSQL in the coming years will be able to significantly push the leaders in the development of complex information systems.