Advantages of DBMS
The database management system has a number of advantages as compared to traditional computer file-based processing approach. The DBA must keep in mind these benefits or capabilities during databases and monitoring the DBMS.
The Main advantages of DBMS are described below.
Centralized Data Management: Large commercial databases may exist in two different Topologies.
1. Centralized – A centralized database (sometimes abbreviated CDB) is a database that is located, stored, and maintained in a single location. This location is most often a central computer or database system, for example a desktop or server, or a mainframe computer. Users typically use an Internet connection and network of computers to access a CDB. In most cases, a centralized database would be used by an organization (e.g. a business company) or an institution (e.g. a university). Banks, airlines, railways etc., tend to use centralized databases.
2. Distributed – Where the database is in many locations often where you have a national or international company and customers tend to regularly interact with a local branch. For example: Google uses a distributed DBMS to cater to users in different geographic regions to dispense country/region specific information.
In both cases the database “looks” like one database – the end-user cannot feel the difference. Information stored in Centralized databases is accessible from a large number of different points, which in turn creates a significant amount of advantages as against other types of databases. Some of the important advantages are listed below:
1. Data integrity is maximized and data redundancy is minimized, as the single storing place of all the data also implies that a given set of data only has one primary record. This helps in maintaining data accurately and consistently, hence enhancing data reliability.
2. Generally bigger data security, as the single data storage location implies that there is only one possible place where the database can be attacked and sets of data can be stolen or tampered with.
3. Better data preservation than the distributed type since data backup and maintenance becomes easier and less time consuming.
4. Ease of use by the end-user due to the simplicity of a single database design.
5. Generally easier data portability and database administration.
6. More cost effective than other types of database systems as labor, power supply and maintenance costs are all minimized.
7. Data kept in the same location is easier to be edited, updated, re-organized, mirrored, or analyzed.
8. All the information can be accessed at the same time from the same location.
9. Updates to any given set of data are immediately received by every end-user.
Data Independence: In a database, the management system provides the interface between the application programs and the data. Data independence refers to the immunity of user applications to changes made in the data structure and organization or storage. Physical data independence means the applications need not worry about how the data are physically structured and stored. Applications should work with a logical data model and declarative query language.
If major changes were to be made to the data, the application programs may need to be rewritten. When changes are made to the data representation, the data maintained by the DBMS is changed but the DBMS continues to provide data to application programs in the previously used ways.
Data independence is the immunity of application programs to changes in storage structures and access techniques. For example if we add a new attribute, change index structure then in traditional file processing system, the applications are affected. But in a DBMS environment these changes are reflected in the catalog. As a result the applications are not affected. Data independence can be physical data independence or logical data independence.
· Physical data independence is the ability to modify physical schema without causing the conceptual schema or application programs to be rewritten. In effect, it means that different kinds of user applications are able to interact with the data irrespective of the structure of the data in the database.
· Logical data independence is the ability to modify the conceptual schema without having to change the external schemas or application programs. Logical Data independence means if we add some new columns or remove some columns from table then the user view and programs will not change.
Data independence and operation independence together define “Data Abstraction”.
Data Inconsistency: Data inconsistency means different copies of the same data will have different values. For example, consider a person working in a branch of an organization.
The details of the person will be stored both in the branch office as well as in the main office. If that particular person changes his address, then the “change of address” has to be maintained in the main as well as the branch office. For example the “change of address” is maintained in the branch office but not in the main office, then the data about that person is inconsistent.
DBMS is designed to have data consistency. Some of the qualities achieved in DBMS are:
Explanation of Terms:
· Data redundancy means duplication of data. Data redundancy will occupy more space hence it is not desirable.
· Data independence means independence between application program and the data. The advantage is that when the data representation changes, it is not necessary to change the application program.
· Data inconsistency means different copies of the same data will have different values.
· Centralizing the data means data can be easily shared between the users but the main concern is data security.
· The main threat to data integrity comes from several different users attempting to update the same data at the same time. For example, “The number of bookings made is larger than the capacity of the aircraft/train.”
· Support for multiple views means DBMS allows different users to see different “views” of the database, according to the perspective each one requires. This concept is used to enhance the security of the database.
Other Advantages of DBMS
Controlling Data Redundancy
In non-database systems each application program has its own private files. In this case, the duplicated copies of the same data is created in many places. In DBMS, all data of an organization is integrated into a single database file. The data is recorded in only one place in the database and it is not duplicated.
In DBMS, data can be shared by authorized users of the organization. The database administrator manages the data and gives rights to users to access the data. Many users can be authorized to access the same piece of information simultaneously. The remote users can also share same data. Similarly, the data of same database can be shared between different application programs.
By controlling the data redundancy, the data consistency is obtained. If a data item appears only once, any update to its value has to be performed only once and the updated value is immediately available to all users. If the DBMS has controlled redundancy, the database system enforces consistency.
In Database management system, data in database is stored in tables. A single database contains multiple tables and relationships can be created between tables (or associated data entities). This makes easy to retrieve and update data.
Integrity constraints or consistency rules can be applied to database so that the correct data can be entered into database. The constraints may be applied to data item within a single record or they may be applied to relationships between records.
Form is very important object of DBMS. You can create forms very easily and quickly in DBMS. Once a form is created, it can be used many times and it can be modified very easily. The created forms are also saved along with database and behave like a software component. A form provides very easy way (user-friendly) to enter data into database, edit data and display data from database. The non-technical users can also perform various operations on database through forms without going into technical details of a fatabase.
Most of the DBMSs provide the report writer tools used to create reports. The users can create very easily and quickly. Once a report is created, it can be used may times and it can be modified very easily. The created reports are also saved along with database and behave like a software component.
Control over Concurrency
In a computer file-based system, if two users are allowed to access data simultaneously, it is possible that they will interfere with each other. For example, if both users attempt to perform update operation on the same record, then one may overwrite the values recorded by the other. Most database management systems have sub-systems to control the concurrency so that transactions are always recorded with accuracy.
Backup and Recovery Procedures
In a computer file-based system, the user creates the backup of data regularly to protect the valuable data from damage due to failures to the computer system or application program. It is very time consuming method, if amount of data is large. Most of the DBMSs provide the 'backup and recovery' sub-systems that automatically create the backup of data and restore data if required.
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