merge method

HyperLogLogUtils merge(
  1. HyperLogLogUtils other
)

Merges other into a new sketch (both must share this precision).

Register-wise max is the exact merge rule for HLL: the union's rank in a bucket is whichever sketch saw the longer leading-zero run there, so merging never loses information. Differing precision throws. Audited: 2026-06-12 11:26 EDT

Implementation

HyperLogLogUtils merge(HyperLogLogUtils other) {
  if (other.precision != precision) {
    throw ArgumentError.value(
      other.precision,
      'other.precision',
      'must equal this.precision ($precision)',
    );
  }
  final HyperLogLogUtils out = HyperLogLogUtils(precision: precision);
  for (int i = 0; i < _registers.length; i++) {
    out._registers[i] = math.max(_registers[i], other._registers[i]);
  }
  return out;
}