Database software mainly consists of two segments: online transaction processing and data warehousing.

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In essence, Hadoop replaces the role of OLAP (online analytical processing) in preparing data to answer specific questions.

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This is especially true in online analytical processing, which stores the data in an optimal form to support specific types of analysis.

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They reside on a PC and use its processing horsepower but also continually refresh with data from an online stream.

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