What are the advantages of distributed database over centralized database?
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The distribution of data and applications has potential advantages over traditional centralized database systems. Unfortunately, there are also disadvantages; in this section we review the advantages and disadvantages of DDBMS. Show
Advantage and Disadvantage of Distributed Database Management SystemThere are some Advantage and Disadvantage of Distributed Database Management System are as follow Advantages of Distributed Database Management System (DDBMS)Following are the advantages of distributed databases over centralized databases. 1. Modular DevelopmentIf the system needs to be expanded to new locations or new units, in centralized database systems, the action requires substantial efforts and disruption in the existing functioning.
However, in distributed databases, the work simply requires adding new computers and local data to the new site and finally connecting them to the distributed system, with no interruption in current functions. 2. More ReliableIn case of database failures, the total system of centralized databases comes to a halt. However, in distributed systems, when a component fails, the functioning of the system continues may be at a reduced performance. Hence DDBMS is more reliable.3. Better ResponseIf data is distributed in an efficient manner, then user requests can be met from local data itself, thus providing faster response. On the other hand, in centralized systems, all queries have to pass through the central computer for processing, which increases the response time.4. Lower Communication CostIn distributed database systems, if data is located locally where it is mostly used, then the communication costs for data manipulation can be minimized. This is not feasible in centralized systems.5. Improved PerformanceAs the data is located near the site of 'greatest demand', and given the inherent parallelism of distributed DBMSs, speed of database access may be better than that achievable from a remote centralized database.
Furthermore, since each site handles only a part of the entire database, there may not be the same contention for CPU and I/O services as characterized by a centralized DBMS. 6. Improved share ability and local autonomyThe geographical distribution of an organization can be reflected in the distribution of the data; users at one site can access data stored at other sites.
Data can be placed at the site close to the users who normally use that data. In this way, users have local control of the data, and they can consequently establish and enforce local policies regarding the use of this data.
A global database administrator (DBA) is responsible for the entire system. Generally, part of this responsibility is assigned the local level, so that the local DBA can manage the local DBMS. Disadvantages of Distributed Database Management System (DDBMS)There are following disadvantages of distributed database: 1. ComplexityA distributed DBMS that hides the distributed nature from the user and provides an acceptable level of performance, reliability, availability is inherently more complex then a centralized DBMS. The fact that data can be replicated also adds an extra level of complexity to the distributed DBMS. If the software does not handle data replication adequately, there will be degradation in availability, reliability and performance compared with the centralized system, and the advantages we cites above will become disadvantages. 2. CostIncreased complexity means that we can expect the procurement and maintenance costs for a DDBMS to be higher than those for a centralized DBMS. Furthermore, a distributed DBMS requires additional hardware to establish a network between sites. There are ongoing communication costs incurred with the use of this network. There are also additional labor costs to manage and maintain the local DBMSs and the underlying network. 3. SecurityIn a centralized system, access to the data can be easily controlled. However, in a distributed DBMS not only does access to replicated data have to be controlled in multiple locations but also the network itself has to be made secure. In the past, networks were regarded as an insecure communication medium. Although this is still partially true, significant developments have been made to make networks more secure. 4. Integrity control more difficultDatabase integrity refers to the validity and consistency of stored data. Integrity is usually expressed in terms of constraints, which are consistency rules that the database is not permitted to violate. Enforcing integrity constraints generally requires access to a large amount of data that defines the constraints. In a distributed DBMS, the communication and processing costs that are required to enforce integrity constraints are high as compared to centralized system. 5. Lack of StandardsAlthough distributed DBMSs depend on effective communication, we are only now starting to see the appearance of standard communication and data access protocols. This lack of standards has significantly limited the potential of distributed DBMSs. There are also no tools or methodologies to help users convert a centralized DBMS into a distributed DBMS 6. Lack of experienceGeneral-purpose distributed DBMSs have not been widely accepted, although many of the protocols and problems are well understood. Consequently, we do not yet have the same level of experience in industry as we have with centralized DBMSs. For a prospective adopter of this technology, this may be a significant deterrent. 7. Database design more complexBesides the normal difficulties of designing a centralized database, the design of a distributed database has to take account of fragmentation of data, allocation of fragmentation to specific sites, and data replication. What are the main potential advantages of distributed databases compared with centralized database?Better Response. Efficient data distribution in a distributed database system provides a faster response when user requests are met locally. In centralized databases, user requests pass through the central machine, which processes all requests.
What are the advantages and disadvantages of a distributed database management system over a centralized DBMS?It is difficult to maintain data integrity in the distributed database because of its nature. There can also be data redundancy in the database as it is stored at multiple locations. The distributed database is complicated and it is difficult to find people with the necessary experience who can manage and maintain it.
What are the three 3 advantages of distributed database systems?1) In a distributed database, data can be stored in different systems like personal computers, servers, mainframes, etc. 2) A user doesn't know where the data is located physically. Database presents the data to the user as if it were located locally. 3) Database can be accessed over different networks.
What is difference between centralized and distributed database?A distributed database is the term used to describe a set of databases stored on multiple computers, but that present as a single database to users. A centralized database is stored at a single location; a mainframe computer, for instance. It can be accessed, maintained and modified only from that location.
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