What is a key disadvantage of a distributed database system?

A key disadvantage of a distributed database system is its susceptibility to data inconsistency. In a distributed environment, data is stored across multiple locations or nodes, which can lead to challenges in maintaining synchronization. When transactions occur, if updates are made to the same piece of data at different locations without proper coordination, inconsistencies can arise. This situation often necessitates complex algorithms and protocols to ensure that all parts of the system have the correct and updated information, increasing complexity and potential for errors.

This inconsistency is particularly problematic in scenarios where data must be accurate and current, such as in financial applications or systems requiring real-time updates. Unlike centralized database systems, where data access is controlled from a single point, distributed databases need mechanisms like distributed locking and consistency models to manage updates, which can lead to delays and performance issues if not handled effectively.

Therefore, while distributed systems offer advantages such as improved access speed and reduced risk of single points of failure, the challenge of ensuring consistency across multiple sites is a significant disadvantage that must be addressed in their design and operation.