Introduction and MapReduce - SNAP - Stanford University

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Either the I/O (communication) or processing (computation) cost dominates Ignore one or the other Total costs tell what you pay in rent from your friendly neighborhood cloud Elapsed costs are wall-clock time using parallelism 1/8/2012 Jure Leskovec, Stanford CS246: Mining Massive Datasets, http://cs246.stanford.edu 59
Total communication cost = O(|R|+|S|+|R ⋈ S|) Elapsed communication cost = O(s) We’re going to pick k and the number of Map processes so I/O limit s is respected We put a limit s on the amount of input or output that any one process can have. s could be: What fits in main memory What fits on local disk With proper indexes, computation cost is linear in the input + output size So computation costs are like comm. costs 1/9/2012 Jure Leskovec, Stanford CS246: Mining Massive Datasets, http://cs246.stanford.edu 60
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CS246: Mining Massive Datasets Jure
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Course website: http://cs246.stanfo
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Short weekly quizzes: 20% Short e-
Page 7 and 8: Recitation sessions: Review of pro
Page 9 and 10: CS345a: Data mining got split into
Page 11 and 12: Much of the course will be devoted
Page 13 and 14: High-dimensional data: Locality Se
Page 16 and 17: Discovery of patterns and models th
Page 18 and 19: Scalability Dimensionality Comple
Page 20 and 21: A big data-mining risk is that you
Page 22: He told these people they had ESP a
Page 25 and 26: 20+ billion web pages x 20KB = 400+
Page 27 and 28: Large-scale computing for data mini
Page 29 and 30: Problem If nodes fail, how to stor
Page 31 and 32: Reliable distributed file system D
Page 33 and 34: Case 1: File too large for memory,
Page 35 and 36: Input key-value pairs k k k … v v
Page 37 and 38: Input: a set of key/value pairs Pr
Page 39 and 40: map(key, value): // key: document n
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Page 47 and 48: Fine granularity tasks: map tasks >
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Page 51 and 52: 1/8/2012 Jure Leskovec, Stanford CS
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Page 55 and 56: Use a hash function h from B-values
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Page 63 and 64: Jeffrey Dean and Sanjay Ghemawat: M
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Introduction and MapReduce - SNAP - Stanford University

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