What is Bit Mapped Index? - Data warehousing

What is Bit Mapped Index?

Bitmap indexes make use of bit arrays (bitmaps) to answer queries by performing bitwise logical operations.

They work well with data that has a lower cardinality which means the data that take fewer distinct values.

Bitmap indexes are useful in the data warehousing applications.

Bitmap indexes have a significant space and performance advantage over other structures for such data.

Tables that have less number of insert or update operations can be good candidates.

The advantages of Bitmap indexes are:

- They have a highly compressed structure, making them fast to read.
- Their structure makes it possible for the system to combine multiple indexes together so that they can access the underlying table faster.

The Disadvantage of Bitmap indexes is:

- The overhead on maintaining them is enormous.
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