# `Otel.Metrics.Exemplar.Filter`
[🔗](https://github.com/yangbancode/otel/blob/main/lib/otel/metrics/exemplar/filter.ex#L1)

Exemplar filter — `trace_based` only.

Spec `metrics/sdk.md` L1377-L1379 lists `:always_on`,
`:always_off`, and `:trace_based`; minikube hardcodes
`:trace_based` because it's the only branch that respects
the wire-format input (parent span's W3C `trace_flags`).
Same shape as `Otel.Trace.Sampler`'s preserved `:drop`
decision: a wire-format invariant remains after the
user-policy filters are stripped.

# `should_sample?`

```elixir
@spec should_sample?(ctx :: Otel.Ctx.t()) :: boolean()
```

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*Consult [api-reference.md](api-reference.md) for complete listing*