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A bitmap and a btree indexes are used to retrieve rows faster than a full-table scan.
Below are the basic differences between b-tree and bitmap indexes :
1: Syntax of bitmap and a B-tree indexes:
- The bitmap index includes the "bitmap" keyword.
- The btree index does not say "bitmap"
2: Cardinality differences:
- The bitmap index is generally for low cardinality columns (Columns with duplicate values )
- while b-tree indexes are best for high cardinality columns.
3: Internal structure differences:
- A B-tree index has index nodes (based on data block size), it like a tree form
- A bitmap index looks like this, a two-dimensional array with zero and one (bit) values
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