Expand description
§Compact probabilistic cardinality estimation
A HyperLogLog sketch backed by Blake3 hashing. Used where we need an approximate count of distinct items (for example, unique viewers of a post or unique voters on a piece of feedback) without storing the items themselves — the sketch is a fixed 64 bytes regardless of how many distinct inputs have been seen.
Configured with 2^6 = 64 registers (yielding ~7.8% standard error), which keeps the sketch small enough to embed freely in RPC responses and on-disk records while still being accurate enough for UI-grade counts.