Is it advisable to use indexing for boolean columns in a database for performance reasons?

Boolean column indexing is usually inefficient performance-wise, especially if values are roughly evenly distributed (e.g., 50% true and 50% false). This is because the selectivity of the index (ability to narrow down the search) is low — the index does not help to quickly filter a large number of rows.

Exceptions occur if the boolean column is highly skewed, for example, 99% false and only 1% true. In such cases, the index can speed up queries filtering by the rare value.

In general, it is advisable to evaluate the need for indexing boolean columns based on data analysis and query profiling, rather than creating an index by default.