Multiple choice

Which of the following statements is true when considering the number of indexes to be created on a table?

  1. Every column that is updated requires an index.

  2. Every column that is queried is a candidate for an index.

  3. Columns that are part of a WHERE clause are candidates for an index.

  4. On a table used in a Data Warehouse application there should be no indexes.

  5. All of the above.
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C Correct answer
Explanation

Columns appearing in WHERE clauses are prime candidates for indexing because indexes speed up data retrieval. Not every queried column needs an index (indexes have overhead), and not every updated column should be indexed (indexes slow down updates). Data warehouses do use indexes, just different types.

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