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Statistics over sliding windows

Two approaches to improve the alarm evaluator were discussed at the summit.

Map-reduce approach


Increment/decrement approach


Statistics where increments/decrements are possible:

  • count,
  • sum,
  • average,
  • stddev

Statistics with special implementation:

  • min/max : needs O(log n) space (probably in DB), where n = window size
  • percentile : classical statistics query
  • cardinality : approximate algorithm, extremely efficient

Map-reduce approach covers all these statistics.