Multiple choice technology databases

In which scenario would an index be most useful?

  1. The indexed column is declared as NOT NULL.

  2. The indexed columns are used in the FROM clause.

  3. The indexed columns are part of an expression.

  4. The indexed column contains a wide range of values.
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D Correct answer
Explanation

Indexes are most effective on columns with high cardinality (wide range of unique values). Low-cardinality columns (like boolean flags or status enums) benefit less from indexing because the index doesn't significantly reduce the search space.

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