Bitmap Index
A bitmap index is a database indexing technique that uses bit arrays (bitmaps) to represent the presence or absence of values in a column. It is particularly efficient for low-cardinality columns (columns with few distinct values) and is widely used in data warehousing and OLAP (Online Analytical Processing) systems. Each distinct value in the column has a corresponding bitmap where each bit indicates whether a row contains that value, enabling fast Boolean operations for queries.
Developers should learn and use bitmap indexes when working with data warehousing, business intelligence, or analytical databases where queries involve multiple conditions on low-cardinality columns, such as filtering by categories, statuses, or flags. They are ideal for accelerating complex queries with AND, OR, and NOT operations, as bitmap operations are computationally cheap and can be performed in parallel, leading to significant performance gains in read-heavy environments.