BUSI 3400 Lecture Notes - Lecture 11: Fact Table, Data Cube, Mapreduce
4 May 2017
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Index: a secondary file structure that provides an alternative path to the data. Data sparsity: number of different values a column could have. B+ tree: provides improved performance on sequential and range searches. All keys are redundantly stored in the leaf nodes. Bitmap: strings of bits, one for each row. Index selectivity: measure of the likelihood that an index will be used in query processing. Short-term decisions: fulfill orders, resolve complaints, provide staffing. Decision support processing: uses integrated and summarized data. Medium and long-term decisions: capacity planning, store locations, product promotion, new lines of business. Decision support data: time span, granularity (drill down, roll up), Data warehouse definition characteristics: a central repository for summarized and integrated data from operational databases and external data sources. Provide decision support to a small group of people. Data mart benefits: lower cost and shorter implementation time. Fact table: dimension keys (link fact table to the dimensions),
