History
The concept of bitmap index was first introduced by Professor Israel Spiegler and Rafi Maayan in their research "Storage and Retrieval Considerations of Binary Data Bases", published in 1985. The first commercial database product to implement a bitmap index was Computer Corporation of America's Model 204. Patrick O'Neil published a paper about this implementation in 1987. This implementation is a hybrid between the basic bitmap index (without compression) and the list of Row Identifiers (RID-list). Overall, the index is organized as a B+tree. When the column cardinality is low, each leaf node of the B-tree would contain long list of RIDs. In this case, it requires less space to represent the RID-lists as bitmaps. Since each bitmap represents one distinct value, this is the basic bitmap index. As the column cardinality increases, each bitmap becomes sparse and it may take more disk space to store the bitmaps than to store the same content as RID-lists. In this case, it switches to use the RID-lists, which makes it a B+tree index.
Read more about this topic: Bitmap Index
Famous quotes containing the word history:
“Whenever we read the obscene stories, the voluptuous debaucheries, the cruel and torturous executions, the unrelenting vindictiveness, with which more than half the Bible is filled, it would be more consistent that we called it the word of a demon than the Word of God. It is a history of wickedness that has served to corrupt and brutalize mankind.”
—Thomas Paine (1737–1809)
“Gossip is charming! History is merely gossip. But scandal is gossip made tedious by morality.”
—Oscar Wilde (1854–1900)
“Indeed, the Englishman’s history of New England commences only when it ceases to be New France.”
—Henry David Thoreau (1817–1862)