OpenTelemetry metrics limitations

When sending data from your application via OpenTelemetry, the following limits and limitations apply.

Limits

Entity
Limit
Description
Metric key length, characters
Min: 2, Max: 255
The length of a metric key.
Dimension key length, characters
Min: 1, Max: 100
The length of a dimension key. If the maximum length is exceeded, the key is truncated to 100 characters.
Dimension value length, characters
Min: 1, Max: 255
The length of a dimension value. If the maximum length is exceeded, the dimension value is truncated to 255 characters.
Number of dimensions per metric data point
50
The maximum total number of dimensions in a single metric data point. If the number of dimensions is exceeded, the whole data point is dropped.
Total number of possible metric keys per environment
20,000
The maximum number of metric keys that can be active at the same time.
Number of tuples per month per metric
1,000,000
The maximum number of tuples (unique metric-dimension key-value type combinations) for each metric key for the last 30 days.
Number of tuples per month for all custom metrics
50,000,000
The maximum number of tuples (unique metric-dimension key-value type combinations) for all custom metrics for the last 30 days.
Instrument unit, characters
63
The maximum total length of the instrument unit. If the maximum length is exceeded, the unit is dropped.
Instrument description, characters
1,023
The maximum total length of the instrument description. If the maximum length is exceeded, the instrument description is truncated to 1,023 characters.
Request size
4 MB
The maximum uncompressed size of an OTLP request with a metrics payload. If the limit is exceeded, the entire request is dropped.
Metric data points
15,000
The maximum number of metric data points in an OTLP request with a metrics payload. If the limit is exceeded, the entire request is dropped.

Limitations

Aggregation temporality

The Dynatrace backend exclusively works with delta values and requires the respective aggregation temporality. Please ensure your metrics exporter is accordingly configured or set the OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE environment variable to DELTA.

For examples on how to set the temporality under each individual language, see the integration walkthroughs.

Metric keys

  • A metric key consists of sections separated by dots (for example, dt.metrics).
  • A metric key can contain lowercase and uppercase letters, numbers, hyphens (-), and underscores (_).
  • A metric key must start with a letter character.
  • A metric key must not contain non-Latin characters (such as ä, ö, and ü).
  • A metric key may be suffixed automatically depending on the payload (for example, .count for counters and .gauge for gauges)

If you use characters that are invalid according to the rules above, they will be replaced with underscores. If your metric key does not have at least one valid character, the data point will be dropped.

Dimension keys

  • Dimensions are comparable to span or resources attributes.
  • A dimension key can contain only lowercase letters (not uppercase letters), numbers, hyphens (-), periods (.), and underscores (_).
  • A dimension key must start with a letter character.
  • A dimension key must not contain non-Latin characters (such as ä, ö, and ü).
  • A dimension key can be in the key.key-section format.
  • You can specify up to 50 dimensions.
  • If the same dimension key is specified multiple times in a single payload, only the value that occurs first is accepted.

If you use characters that are invalid according to the rules above, they will be replaced with underscores. If your dimension key does not have at least one valid character, the key will be dropped.

Dimension values must be passed as a string, Boolean, or integer.

Dynatrace does not support non-string dimensions and will convert Booleans and integers to strings upon ingest.

If any other type is used, the entire dimension will be dropped.

Histograms

  • For Exponential Histogram, Dynatrace ingests the histogram's min|max|sum|count but doesn't ingest the buckets.

If any of below happens, the OpenTelemetry ingest API returns the 400 or 200 with partial success responses.

  • Cumulative histograms aren't ingested (similarly to cumulative counters)
  • Histogram data points without sum aren't ingested. This happens when negative values are recorded.
  • Histogram buckets are not sorted
  • Histogram bucket boundary values of NaN or Infinite are invalid.

The Dynatrace OpenTelemetry ingest API only returns an HTTP 400 when all metrics in the OTLP request are invalid.

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