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8 lines
759 B
TeX
8 lines
759 B
TeX
For groups of data that don't change often, we can compute statistics on insert, such as \texttt{sum}, \texttt{avg}, \texttt{min}, \texttt{max}, etc.
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These aggregates can be used to check whether data needed is within that group.
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This also enable computing (some) aggregates without reading the entire table and is commonly used in data mining and data cubes.
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A concept that is not used in DB engines, is count min sketch. It can be very useful in data streaming engines and large scale data processing.
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What this does is it computes statistics on how many times a given value was seen in a list or stream of data and is a variation of the bloom filter,
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but with several arrays and counting. The overestimation in count is bounded by the size in the matrix.
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