Setup

Run stackdriver_exporter with --monitoring.metrics-type-prefixes=bigtable.googleapis.com.

Expected

Metrics like stackdriver_bigtable_table_bigtable_googleapis_com_server_latencies_count should present as monotonically increasing counters, as would normal Prometheus histogram counters.

Actual

Metrics stackdriver_bigtable_table_bigtable_googleapis_com_server_latencies_count frequently decrement and oscillate in ways they shouldn't.

Screenshot:

This inherently throws off quantile calculations on the respective histogram buckets, as the individual bucket counts oscillate in the same manner. This yields per-bucket rates that provide errant quantiles (ex: 47-day-long latency measurements on p50).