Differences between databases and file systems during work Accumulation

Early database management adopted file systems. In a file system, data consists of several named files based on their content, structure, and usage. Files are generally owned by a user or user group, but can be shared by other users. Users can open, read, write, and close files through the operating system.

File systems have obvious disadvantages:
(1) it is inconvenient to write applications.
The Application Designer must have a clear understanding of the logic and physical structure of the files used. The operating system can only open, close, read, write, and other low-level file operation commands, query and modification of files and other processing must be addressed in the application. Applications also inevitably repeat functions. Writing applications on a file system is not efficient.
(2). File design is difficult to meet different requirements of a variety of applications. data redundancy is often inevitable.
To meet the requirements of various applications, redundant data is often required when designing a file system. Data redundancy not only wastes space, but also leads to inconsistency of data. The file system does not have a monitoring mechanism for maintaining data consistency. Data Consistency is completely maintained by users. It is barely possible to cope with a simple system, but it is almost impossible to accomplish it in a large and complex system.
(3) modifying the file structure will lead to application modification, and the maintenance of the application will be large.
(4). The file system does not support concurrent access to files (concurrent access ).
(5 ). data lacks unified management, and it is difficult to standardize and standardize the data structure, encoding, representation format, naming, and output format. In terms of data security and confidentiality, it is also difficult to take effective measures.

To address the disadvantages of file systems, we have developed a database system featuring unified management and data sharing. In a database system, data does not only serve a program or user, but is considered as a shared resource of a Unit. A database management system (DBMS) software management. With the centralized management of DBMS, applications do not have to directly intervene in low-level operations such as opening, closing, and reading/writing files, but are handled by DBMS. Users do not have to worry about data storage and other implementation details, so they can observe and access data at a higher abstraction level. Some modifications to the file structure can also be blocked by DBMS, so that users cannot see these modifications, thus reducing the maintenance workload of applications and improving data independence. Because of the unified management of data, people can focus on the entire unit and Reasonably organize data to reduce data redundancy. In addition, they can better implement standardization and standardization, this facilitates data transfer and wider sharing. Since DBMS does not serve an application but the whole unit, it is acceptable to make DBMS more complex. Many of the kinetic energy that is hard to implement in a file system is implemented in DBMS.

For example, it is suitable for multiple user interfaces of different types of users. It ensures concurrent control for data consistency during concurrent access and improves access control for data security ), in case of a fault, ensure the data consistency recovery (recovery) function, and ensure the integrity constraints (integrity constraints) check function of the data in terms of semantics. With the development of computer applications, DBMS functions become stronger and larger, and complexity and overhead increase. In simple application systems with clear functions and no data sharing, file systems are still used to reduce overhead and improve performance. However, in data-intensive application systems, basically, the database system is used.

The modern database management system should have seven functions:
1. Provides advanced user interfaces
2. Query Processing and Optimization
The query here refers to the user's access requirements for the database, including not only data retrieval, but also modification and definition of new data.
3. Data Directory management
4. Concurrency Control
5. Restoration
6. integrity constraints check
7. Access Control

Data management, like data processing, is the most basic supporting technology of computer systems. Despite the rapid development of computer science and technology, the status of data management has not changed. Data management will continue to develop as an important branch of computer science and technology, and the requirements for data management are also increasing in social informatization.