README.md

HyperLogLog – Estimating the cardinality of a set

• A probabilistic data structure used in order to count unique things
  • Use an algorithm that trade memory for precision
  • Not actually store values

HLLs in Redis is encoded as a Redis string

Commands

• PFADD : add an element to the count with PFADD
• PFCOUNT : Retrieve the current approximation 
of the unique elements added with PFADD so far

> PFADD hll a b c d
(integer) 1
> PFCOUNT hll
(integer) 4