Which of the following is not one of the stages in the evolution of distributed DBMS?

Solution (By Examveda Team)

The evolution of distributed Database Management Systems (DBMS) involves several stages, each representing advancements in architecture and functionality to support distributed data processing.

Option A: Unit of work
The concept of a unit of work represents the earliest stage in the evolution of distributed DBMS. In this stage, transactions are processed as atomic units of work within a single centralized database system. Transactions are executed sequentially, and concurrency control is limited to within the boundaries of a single database.

Option B: Remote unit of work
The stage of remote unit of work builds upon the concept of a unit of work by introducing the capability to execute transactions that involve accessing data located on remote sites. In this stage, transactions may span multiple nodes or sites in a distributed environment, but the processing is still coordinated by a central authority.

Option C: Distributed unit of work
The distributed unit of work stage represents a further advancement where transactions can be processed independently at each participating node or site in a distributed system. Transactions are decomposed into subtransactions, and each subtransaction can be executed autonomously at its respective node. Coordination and synchronization mechanisms are implemented to ensure consistency and isolation across distributed transactions.

Option D: Distributed request
This option does not correspond to a recognized stage in the evolution of distributed DBMS. While distributed requests are integral to distributed database systems, they are typically associated with the execution of transactions or operations rather than representing a distinct evolutionary stage.

Therefore, in the context of the stages in the evolution of distributed DBMS, the correct option is Distributed request (Option D).