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.
The Type I distribution is great for lighting walkways, paths. and sidewalks. This type of lighting is meant to be placed near. the center of the pathway. This provides adequate lighting for. smaller pathways. Type I is a two-way lateral distribution having a preferred lat-. eral width of 15 degrees in the cone of maximum candlepower. The two principal light concentrations are in opposite direc-. tions along a roadway. This type is generally applicable to a luminaire location near the center of a roadway. where the mounting height is approximately equal to the roadway width. Type II. The Type II distribution is used for wide walkways, on ramps and entrance roadways, as well as other long, narrow lighting.