Multiple choice technology performance

What is selectivity of an Index

  1. Ratio of number of distinct values in column/columns to the total number of rows in the table

  2. Ratio of total number of rows in the table to the number of distinct values in column/columns

  3. Ratio of distinct values in the table to the total number of rows in the table

  4. Total number of rows
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Index selectivity is defined as the ratio of distinct values in a column to the total number of rows. Higher selectivity (closer to 1) means the index is more effective because each distinct value points to fewer rows. Option A correctly states this definition. Option B inverts the ratio, and Options C and D are incorrect formulations.

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