Distribution
Distinct values with their occurrence counts - maps to CloudWatch Values and Counts.
Required for percentiles, and opt-in per instrument because memory grows with the number of distinct values and a latency histogram's values are near-unique.
Parameters
values
value to occurrence count. Chunked at export to the backend's pair limit.
truncated
true when the distinct-value bound was reached and further new values were discarded, so an exporter can warn rather than let partial data read as complete.