Cardinality Estimation (Cardinality Estimation)
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Description
Given a multiset of (possibly hashed) values, estimate the number of distinct elements of the multiset. Of interest is minimizing storage usage.
Parameters
$N$: number of values in multiset
$n$: cardinality of multiset (not known)
Table of Algorithms
| Name | Year | Time | Space | Approximation Factor | Model | Reference |
|---|---|---|---|---|---|---|
| Naive solution | 1940 | $O(N)$ | $O(n)$ | Exact | Deterministic | |
| Flajolet–Martin algorithm | 1984 | $O(N)$ | $O(log n)$ | Randomized | Time & Space | |
| LogLog algorithm | 2003 | $O(N)$ | $O(log(log(n)$)) | Randomized | Time & Space | |
| HyperLogLog algorithm | 2007 | $O(N)$ | $O(eps^{-2}*log(log(n)$))+log(n)) | Randomized | Time & Space | |
| HyperLogLog++ | 2014 | $O(N)$ | $O(eps^{-2}*log(log(n)$))+log(n)) | Randomized | Time |
Time Complexity Graph
