Multiple choice technology databases

What is filter factor?

  1. One divided by the number of distinct values of a column.

  2. Zero divided by the number of distinct values of a column.

  3. Zero divided by the number of distinct values of a row.

  4. One divided by the number of distinct values of a Rrow.
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Explanation

Filter factor (or selectivity) is a measure used by query optimizers to estimate the fraction of rows that satisfy a predicate. For an equality predicate on a column with a uniform distribution, it is calculated as 1 divided by the number of distinct values (NDV).

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