Backend & systems·Observability and operations
you add user id as a label and your metrics bill and query latency both go up by three orders of magnitude.
Metric cardinality explosion
Also calledhigh cardinality labels
The multiplicative growth in stored time series when a label has many distinct values. Every unique combination of label values is a separate series, so one unbounded label — user id, URL with ids in it, error message — can create millions. It is the standard way to take down a metrics backend from inside your own application.