DBMS (database management systems) is a set of software and hardware tools that allows user to manage databases: create, edit and delete data, search the database, customize access levels. A database is a repository of information; a management system is a tool for control and administration.
Key functions of DBMS
- Organizing interaction with information stored in RAM or SSD drives.
● Working with data stored on external storage devices.
● Logging of work stages when accessing the database.
● Support for various database formats.
Structure of DBMS
- Core: regulates data exchange in RAM and on external drives, records all changes.
- Compiler (database language processor): processes user queries, converts them into machine commands, and then returns the results.
- Utilities: program shells and user interaction interfaces that are required for entering commands.
- Database: a place where information is stored and where data is arranged in a specific way.
DBMS are classified by the type of database storage, query processing model and data organization structure.
Storage types
- Local. All DBMS elements are located on a single server.
- Distributed. Elements are distributed across different servers or in cloud environments.
Storage, data and query processing
- Client-server. Databases are located on a single server to which users send queries.
- File-server. Databases are stored on a file server, and management systems are stored on each of the devices from which a query is sent to the database.
- Embedded. DBMS that are used locally as a module to control data within individual applications.
Structure of data organization
- Relational. Management systems for databases where data is represented in the form of tables. In particular, relational DBMS are used for real-time transaction processing.
- Key-value. DBMS for databases where each data unit is assigned a unique identifier consisting of two parts: key and value.
- Document-based. Management systems for databases that store documents with structured text: archives, activity logs, catalogs, etc.
- Graphs. The basic example of a graph scheme is an airline flight map: city points are the vertices of the structure, and flight lines connecting them are the edges. Graph DBMS are used to organize the work of social networks, when it is necessary to store information about connections between users.
- Columnar. The logical model of a columnar DBMS is similar to the relational type: it consists of rows grouped into tables. At the same time, the special “columnar” way of organizing the information in the database implies a higher reading speed when it is necessary to work with a very large amount of data.
- Time series DBMS. These DBMS are optimized for working with timestamps containing time values. This can be data from motion sensors, metrics from market trade indicators, network data, etc.
- Object-oriented. These DBMS were originally created for developers who use object-oriented programming models in their work. Similar systems are used in 3D modeling applications, telecommunications, and scientific software (molecular physics, astronomy, etc.).
- Searchable. This type of DBMS is used for text search in various sources: other databases, text documents, e-mail, RSS feeds, etc.
- Spatial database management systems (SDBMS). These systems were created to work with objects oriented in geometric space. They are optimized both for interaction with simple geometric objects (points, segments, geometric figures) and complex 3D structures.