UGC-NET | UGC NET CS 2016 Aug – III | Question 8

The Global conceptual Schema in a distributed database contains information about global relations. The condition that all the data of the global relation must be mapped into the fragments, that is, it must not happen that a data item which belongs to a global relation does not belong to any fragment, is called:
(A) Disjointness condition
(B) Completeness condition
(C) Reconstruction condition
(D) Aggregation condition

Answer: (B)
Explanation: The condition that all the data of the global relation must be mapped into the fragments, that is, it must not happen that a data item which belongs to a global relation does not belong to any fragment, is called Completeness condition.
In distributed system it is convenient that fragment to be disjoint, so that the replication of data can be controlled explicitly at the allocation level.this is called Disjointness condition
To reconstruct any global relation from its fragment is called Reconstruction condition.
The formation of no. of fragments into a cluster is called Aggregation condition.
So, option (B) is correct.

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