The database commonly uses an index range scan to access selective data. The selectivity is the percentage of rows in the table that the query selects, with 0 meaning no rows and 1 meaning all rows. Selectivity is tied to a query predicate, such as WHERE last_name LIKE 'A%', or a combination of predicates.
Types of Distribution: Intensive, Selective and Exclusive Distribution. Some of the important types of distribution in international market are 1. Intensive 2. Selective and 3. Exclusive distribution.
Data can be distributed (spread out) in different ways. But there are many cases where the data tends to be around a central value with no bias left or right, and it gets close to a Normal Distribution like this: A Normal Distribution. The Bell Curve is a Normal Distribution.