DBMS (Database Management System)

key features

The DBMS provides:

• interaction with information stored on external drives;
• working with “hot” data located in RAM or on SSD;
• logging each step when working with the database;
• support for most database formats;
• support for most database formats;

What goes into a DBMS

The DBMS consists of:

• Kernel. Supports reporting, responsible for managing data in RAM and on external drives.
• Database Language Processor. Processes incoming user or administrator commands. Optimizes requests for data creation and modification.
• Runtime Support Subsystems. Allows interpreting software solutions with current databases, as well as creating user interaction interfaces (APIs) with DBMSs.
• Supporting Software. System utilities that provide additional database management and administration functions.

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Types of DBMS

DBMSs are classified into different types depending on the models of data used, the ways of providing access to the database, and the level of distribution.

Depending on the data model DBMSs are:

• network;
• hierarchical;
• relational;
• object-relational;
• object-oriented;

Based on the method of providing access to the database, DBMSs are divided into:

• embedded;
• client-server;
• “file-server;

Based on the level of distribution DBMSs are:

• geo-distributed (constituent elements of a single DBMS are distributed on different equipment, which can be geographically located in different places);
• local (the software is installed in one data center).

DBMS interaction schemes with external memory

Database management systems can work with information on external storage media by deferred and direct writing. Database management systems can work with information on external storage media by deferred and direct writing.

With deferred writing, changes to the database are written to exchange buffers on external storage devices until:

• Control point. The administrator specifies its parameters in advance.
• Lack of free space for writing on the drive. In this case, a response about lack of free disk space is received.
• Lack of RAM to provide buffers. An error appears about RAM buffer overflow and inability to perform other operations.
• The database stops.

Direct write DBMS writes any changes in the database to external media in real time. The process resembles synchronous replication.