The dependency preservation decomposition is a property to decompose database…
The dependency preservation decomposition is a property to decompose database schema D, in which each functional dependency X → Y specified in
Answer: C. both (A) and (B) — Dependency preservation requires that all original functional dependencies can be derived from the union of projections on decomposed relations. This implies…
- A.
appeared directly in one of the relation schemas Rᵢ in the decomposed D.
- B.
could be inferred from dependencies that appear in some Rᵢ.
- C.
both (A) and (B)
- D.
None of these
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Correct answer: C
Dependency preservation requires that all original functional dependencies can be derived from the union of projections on decomposed relations. This implies inference is sufficient, meaning dependencies do not need to appear directly in a single schema but must be logically implied by the projected set.
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