Bitmap Index - History

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:

    We don’t know when our name came into being or how some distant ancestor acquired it. We don’t understand our name at all, we don’t know its history and yet we bear it with exalted fidelity, we merge with it, we like it, we are ridiculously proud of it as if we had thought it up ourselves in a moment of brilliant inspiration.
    Milan Kundera (b. 1929)

    In history as in human life, regret does not bring back a lost moment and a thousand years will not recover something lost in a single hour.
    Stefan Zweig (18811942)

    Revolutions are the periods of history when individuals count most.
    Norman Mailer (b. 1923)