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dmathieu merged 2 commits into from
Mar 19, 2026
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Cleanup exemplar featuregate readme #8072

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cleanup exemplar featuregate readme
dashpole Mar 18, 2026
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Merge branch 'main' into cleanup_exemplar
dashpole Mar 18, 2026
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63 changes: 0 additions & 63 deletions sdk/metric/internal/x/README.md
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Expand Up @@ -8,69 +8,6 @@ See the [Compatibility and Stability](#compatibility-and-stability) section for

## Features
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- [Exemplars](#exemplars)

### Exemplars

A sample of measurements made may be exported directly as a set of exemplars.

This experimental feature can be enabled by setting the `OTEL_GO_X_EXEMPLAR` environment variable.
The value of must be the case-insensitive string of `"true"` to enable the feature.
All other values are ignored.

Exemplar filters are a supported.
The exemplar filter applies to all measurements made.
They filter these measurements, only allowing certain measurements to be passed to the underlying exemplar reservoir.

To change the exemplar filter from the default `"trace_based"` filter set the `OTEL_METRICS_EXEMPLAR_FILTER` environment variable.
The value must be the case-sensitive string defined by the [OpenTelemetry specification].

- `"always_on"`: allows all measurements
- `"always_off"`: denies all measurements
- `"trace_based"`: allows only sampled measurements

All values other than these will result in the default, `"trace_based"`, exemplar filter being used.

[OpenTelemetry specification]: https://github.com/open-telemetry/opentelemetry-specification/blob/a6ca2fd484c9e76fe1d8e1c79c99f08f4745b5ee/specification/configuration/sdk-environment-variables.md#exemplar

#### Examples

Enable exemplars to be exported.

```console
export OTEL_GO_X_EXEMPLAR=true
```

Disable exemplars from being exported.

```console
unset OTEL_GO_X_EXEMPLAR
```

Set the exemplar filter to allow all measurements.

```console
export OTEL_METRICS_EXEMPLAR_FILTER=always_on
```

Set the exemplar filter to deny all measurements.

```console
export OTEL_METRICS_EXEMPLAR_FILTER=always_off
```

Set the exemplar filter to only allow sampled measurements.

```console
export OTEL_METRICS_EXEMPLAR_FILTER=trace_based
```

Revert to the default exemplar filter (`"trace_based"`)

```console
unset OTEL_METRICS_EXEMPLAR_FILTER
```

## Compatibility and Stability

Experimental features do not fall within the scope of the OpenTelemetry Go versioning and stability [policy](../../../../VERSIONING.md).
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