The GATE Grind

GATE 2025 DA – Question 16

Database Management and Warehousing · Integrity constraints and normal forms · 1 mark · Multiple choice

If a relational decomposition is not dependency-preserving, which one of the following relational operators will be executed more frequently in order to maintain the dependencies?

  1. Selection
  2. Projection
  3. Join
  4. Set union

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Correct answer: (C) Join

Explanation

If the decomposition is not dependency-preserving, some functional dependency involves attributes that now sit in different relations. To check it after an update the relations have to be joined first, which is expensive. So the join operator is the one run more often.