Understand OpenTelemetry Metric Names and Labels

Because Dash0 is OpenTelemetry-native, metric names are stored and queried differently from a traditional Prometheus setup. Understanding the distinction between otel_metric_nameCopy and the translated Prometheus name avoids a common class of PromQL errors.

Dual Naming: OpenTelemetry and Prometheus

When OpenTelemetry metrics are sent to Dash0, they maintain their original names while also being exposed with Prometheus-compatible names according to the OpenTelemetry specification. This dual-naming approach gives you flexibility in how you query your data.

For example, an OpenTelemetry metric named k8s.pod.memory.working_setCopy is also exposed in Prometheus format as k8s_pod_memory_working_set_bytesCopy. Both names refer to the same underlying metric data, and you can use either in your queries.

The otel_metric_nameCopy Attribute

Every metric ingested by Dash0 carries a special otel_metric_nameCopy label that holds the original OpenTelemetry metric name — for example, app.ads.ad_requestsCopy or dash0.logsCopy. This attribute is not sent by your instrumentation; Dash0 derives it from the metric's own identity metadata (alongside otel_metric_typeCopy and otel_metric_unitCopy).

Using otel_metric_nameCopy in a PromQL selector is the recommended approach for most users:

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increase({otel_metric_name="app.ads.ad_requests", otel_metric_type="sum"}[2m])

This works regardless of how the underlying metric name has been translated for Prometheus compatibility and stays stable even if the metric type or unit changes.

You can equivalently query using the Prometheus-compatible name directly:

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k8s_pod_memory_working_set_bytes{service_name="adservice"}

The easiest way to discover Prometheus-compatible names is the Query Builder's autocomplete — once you type a prefix, it shows all matching metric names.

The otel_metric_typeCopy and otel_metric_unitCopy Attributes

Alongside otel_metric_nameCopy, Dash0 adds two more labels to every metric:

• otel_metric_typeCopy — the OTLP data model type. Valid values are sumCopy, gaugeCopy, histogramCopy, exponential_histogramCopy, and summaryCopy (always lowercase in PromQL).
• otel_metric_unitCopy — the unit declared in the metric definition (e.g., sCopy, ByCopy, 1Copy), if one was provided.

The table below maps each otel_metric_typeCopy value to its OTLP type, the OTel API instrument it corresponds to, and how it appears in the Metrics Explorer UI:

Use otel_metric_typeCopy in PromQL to disambiguate metrics that share a name but differ in type:

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{otel_metric_name="app.frontend.requests", otel_metric_type="sum"}

The Prometheus Name Transformation

Prometheus requires metric names to match the pattern [a-zA-Z_:][a-zA-Z0-9_:]*Copy. Dash0 applies the standardised OpenTelemetry-to-Prometheus mapping when exposing metrics via a Prometheus-compatible endpoint. The mapping applies these transformations:

• Type suffixes are added (e.g. _totalCopy for counters).
• Unit suffixes may be added (e.g. _secondsCopy, _bytesCopy).
• Invalid characters (dots, hyphens) are replaced with underscores.
• Multiple consecutive underscores are collapsed into one.

Note that in PromQL selectors, dots in label names are also replaced with underscores — for example, k8s.deployment.nameCopy becomes k8s_deployment_nameCopy.

Choosing Which Name to Use

Common Pitfall: Dots in Metric Names

A frequent error is using OpenTelemetry metric names directly as the PromQL metric selector without wrapping them in a label matcher. Dots are not valid in bare PromQL metric names and will cause a parse error:

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# Error: unexpected character '.'
jvm.memory.used.bytes{service.name="catalog", jvm.memory.type="heap"}

Fix this by using otel_metric_nameCopy or the Prometheus-compatible translated name:

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# Option 1: otel_metric_name label matcher (recommended)
{otel_metric_name="jvm.memory.used.bytes", service_name="adservice", jvm_memory_type="heap"}

# Option 2: Prometheus-compatible name
jvm_memory_used_bytes{service_name="adservice", jvm_memory_type="heap"}

Sending Prometheus Metrics to Dash0

The best way to send Prometheus metrics to Dash0 is via the OpenTelemetry Collector. See our integration documentation for setup instructions.

Further Reading

• Query Metrics in the Query Builder — practical guidance on writing PromQL in Dash0, including common pitfalls around step sizes and cardinality.
• Understand Synthetic Metrics — how otel_metric_nameCopy applies to log, span, and web event metrics.
• Write Effective PromQL Queries — a reference of query patterns for gauges, histograms, summaries, and synthetic metrics.