Which type of index is a grid of bits where each index row corresponds to a unique row in a table?

A bitmap index is a specialized structure used in databases to efficiently manage and query data, particularly in scenarios involving large datasets with low cardinality (i.e., columns that contain a limited number of distinct values). Each row in the bitmap index corresponds to a unique row in the associated table, and each column represents a different value in the indexed column.

The grid of bits allows for fast searching and retrieval of data because the bits can easily be manipulated using bitwise operations. For example, if a column has three possible values (let's say A, B, and C), the bitmap index might use one row to represent the presence or absence of A, another for B, and another for C in the original table's rows.

This index type is especially useful for analytical queries that involve filtering and aggregating large volumes of data quickly, as it allows the database engine to quickly eliminate rows that do not match the filter criteria by performing bitwise operations on the bitmap values.

In contrast, the other types of indexes mentioned do not share this unique characteristic of being structured as a grid of bits directly corresponding to individual rows in a table. Multi-level, logical, and hash indexes each have distinct methodologies for organizing data and optimizing queries that do not align with