October 19, 2023
October 19, 2023
October 19, 2023
###### Computer-Networks
October 19, 2023
 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
Question 8 Explanation:
Functional Completeness Condition: It is the condition used to check the equivalence(The condition that all the data of the global relation must be mapped into the fragments) between global relation and its fragments after decomposition. When a relation is decomposed into fragments, both global relation and its fragments should be able to determine each other.
For decomposing a global relation, lossless decomposition is the necessary condition but functionally completeness problem is not a necessary condition.
A relation in BCNF may or may not be functionally complete
Question 8 Explanation:
Functional Completeness Condition: It is the condition used to check the equivalence(The condition that all the data of the global relation must be mapped into the fragments) between global relation and its fragments after decomposition. When a relation is decomposed into fragments, both global relation and its fragments should be able to determine each other.
For decomposing a global relation, lossless decomposition is the necessary condition but functionally completeness problem is not a necessary condition.
A relation in BCNF may or may not be functionally complete
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