DBMS - Architecture
The design of a DBMS depends on its architecture. It can be centralized or decentralized or hierarchical. The architecture of a DBMS can be considered as a single level or multi-level. An n-tier architecture n modules, which can be independently modified, altered, changed or replaced.
In a 1-level architecture, the DBMS is the only entity where the user sits directly on the DBMS and uses it. All modifications made here will be made directly on the DBMS itself. It does not provide practical tools for end users. Database designers and programmers normally prefer to use a single tier architecture.
If the architecture of the DBMS is two-tier, then it must have an application through which the DBMS is accessible. Programmers utThey have a 2-level architecture where they access the DBMS by means of an application. Here, the application level is completely independent of the database in terms of operation, design and programming.
A 3-level architecture separates its levels from each other according to the complexity of the users and the way in which they use the data present in the database of data. It is the most used architecture to design a DBMS.
- Database level (data) - At this level, the database resides along with its query processing languages. We also have the relationships that define the data and its constraints at this level.
- Application (Middle) Tier - At this level resides the application server and the programs that access the database. To a user, this application level presents an abstract view of the database.end users ignore the existence of the database beyond the application. At the other end of the spectrum, the database level is not aware of any other user at the application level. Therefore, the application layer sits in the middle and acts as a mediator between the end user and the database.
- User level (overview) - End users operate on this level and they do not know anything about the existence of the database at -beyond this layer. At this layer, several views of the database can be provided by the application. All views are generated by applications that reside in the application level.
The tiered database architecture is highly modifiable, as almost all of its components are independent and can be modified independently.