Saturation and registry metrics
Who computes what
Section titled “Who computes what”| Quantity | Where |
|---|---|
| n_new / n_hit (checkpoint window) | domain registry → slices |
| distinct_keys | PG proc / python count_distinct |
| Homogeneity % | formula B (homogeneity_percent) — single canon |
| Emit gauges | telemetry/prometheus/saturation.py |
DTO: framework/contracts/saturation_slices.py.
processing/partition_loop/dataset_metrics_poller.py schedules snapshots.
Do not put psycopg in telemetry runtime.
Multi-worker caveat
Section titled “Multi-worker caveat”Homogeneity as Prometheus source of truth with workers>1 without driver aggregation is unsafe; see postgres architecture rules.