- Hyperloglog is a probabilistic data structure
- Use the to count unqiue things (technically called cardinality of set) and does not store the data itself
- Encoded as a Redis String
- Conceptually the HLL (Hyperloglog) is like using sets to do the same task
- They are not one hundred percentage accurate (less than 1% error expected)
- By using HyperLogLog we can save a tremendous amount of memeory
- Allows you to maintain count of millions of items with extreme efficiency
- Three commands
- PFADD
- PFCOUNT
- PFMERGE
