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Informatica - What is the difference between Bitmap and Btree index?

asked marvit September 20, 2014 08:05 AM  

What is the difference between Bitmap and Btree index?


1 Answers

answered By Mswami   0  
Bitmap index:
A type of index that uses a string of bits to quickly locate rows in a table.
Bitmap indexes are normally used to index low cardinality columns in a warehouse environment.

Btree index:
A type of index that uses a balanced tree structure for efficient record retrieval.
B-tree indexes store key data in ascending or descending order.

Difference Between B-Tree Index & Bitmap Index:

1. B-tree Index has High cardinality values(usually when we have repeated columns),
where as Bitmap Index has Low Cardinality values(usuall when column have few values like true/false).
2. B-tree Index is userful for OLTP, where as Bitmap Index is useful for Dataware Housing.
3. B-tree index updates on key values has relatively inexpensive, where as Bitmap index has more expensive.

Bitmap indexes are more advantageous than b-tree indexes when the table has millions of rows and the key columns have low cardinality. bitmap indexes provide better performance than b tree indexes when queries often use a combination of multiple where conditions involving the OR operator, the table is read-only, or when there is low update activity on the key columns.
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