Statistics about data (streaming processing):
- Approximate counting using 4, 8, 16 bits of state.
- Cardinality estimation using HyperLogLog, HyperBitBit, linear probabilistic counting, and hybrid. Some implementations only need 64 bits of state.
- Frequent item detection using count-min sketch, count-min-mean sketch, AMS sketch, majority, frequent. Some implementations only need 64 bits of state.
- Cardinality estimation for key-values pairs, by combining count-min-mean sketch and HyperLogLog.
- Approximate histogram using 64 bits of state with 11 buckets, e.g. for lengths.
- Minimum and maximum.
- Approximate median using the remedian algorithm (somewhat improved).
- Random sample using the reservoir sampling algorithm.
- Set reconciliation using IBLT (invertible Bloom lookup table), including a file repair tool similar to PAR2.