SAP suggests that a bitmap index on a column can outperform a B-tree index when:
1. The Cardinality, which can be represented as the number of distinct values is small compared to the number of rows in the table. I can determine this via transaction DB02
2. Bitmap indexes are also ideal when values in a column are repeated more than 100. Can check this i.e. SE11
3. Where cardinality is high, bitmap indexes should be used if there are complex conditions in the WHERE clauses of queries. How can I determine this?