Fourth Normal Form (4NF) perspective: Multivalued dependencies should ________ be eliminated in well-designed operational schemas.

Introduction / Context:
Multivalued dependencies (MVDs) arise when two or more independent multi-valued attributes coexist in a table for the same key. This leads to combinatorial duplication and anomalies. Fourth Normal Form (4NF) addresses this by decomposing tables to remove nontrivial MVDs.

Given Data / Assumptions:

• MVDs create redundancy and update anomalies.
• 4NF recommends decomposing to independent relations.
• Performance or reporting exceptions may exist in practice.

Concept / Approach:

From a theory standpoint, nontrivial multivalued dependencies should be removed to achieve 4NF. In practice, organizations commonly eliminate them but may retain controlled redundancy in rare, performance-driven scenarios with compensating controls. Hence many texts state they should “usually” or “commonly” be eliminated in OLTP design.

Step-by-Step Solution:

Verification / Alternative check:

Measure update and insert anomaly rates before/after decomposition; normalization typically reduces anomalies and storage.

Why Other Options Are Wrong:

Always/Never: too absolute; real systems sometimes keep limited redundancy.

Seldom: understates the frequency with which removal is appropriate.

Common Pitfalls:

Failing to recognize independent repeating sets; attempting to “fix” with triggers instead of proper schema decomposition.

Final Answer:

commonly