Distributed Database - Disadvantages

Disadvantages

• Complexity — extra work must be done by the DBAs to ensure that the distributed nature of the system is transparent. Extra work must also be done to maintain multiple disparate systems, instead of one big one. Extra database design work must also be done to account for the disconnected nature of the database — for example, joins become prohibitively expensive when performed across multiple systems.
• Economics — increased complexity and a more extensive infrastructure means extra labour costs.
• Security — remote database fragments must be secured, and they are not centralized so the remote sites must be secured as well. The infrastructure must also be secured (e.g., by encrypting the network links between remote sites).
• Difficult to maintain integrity — but in a distributed database, enforcing integrity over a network may require too much of the network's resources to be feasible.,
• Inexperience — distributed databases are difficult to work with, and as a young field there is not much readily available experience on proper practice.
• Lack of standards — there are no tools or methodologies yet to help users convert a centralized DBMS into a distributed DBMS.
• Database design more complex — besides of the normal difficulties, the design of a distributed database has to consider fragmentation of data, allocation of fragments to specific sites and data replication.
• Additional software is required.
• Operating System should support distributed environment.
• Concurrency control: it is a major issue. It can be solved by locking and timestamping.