Summary
Dashboard widgets do not support computed expressions across metric queries. Users need to create derived metrics — such as occurred / total = occurrence percentage — directly in dashboard widgets without relying on pre-aggregated custom metrics or workarounds in alerting.
Current behavior
Dashboard widgets support individual metric queries (e.g. count of spans matching a filter) but have no way to compose two metric values into a formula. Users who want to display a ratio or percentage must either:
- Track the derived metric externally before ingestion
- Switch to Discover/Explore (which supports equations but has limited metric querying and no persistent dashboard widget path)
- Use Metric Alerts with equations (ISWF-1927), which does not surface in dashboards
Gap
Dashboards are the primary surface for ongoing visibility into system health. Without formula support, any ratio-based KPI (occurrence rate, error rate, success rate) cannot be expressed as a first-class widget. Users must instrument derived values at the SDK level or maintain separate pipelines, increasing toil and reducing dashboard utility.
Options
- Equation support in widget builder: Allow users to define a formula referencing two or more metric queries (e.g.
a / b, a / (a + b) * 100), following the model already in place for transaction-based Discover widgets. Numerator and denominator queries are configured independently; the result drives the chart/number widget.
- Virtual/derived metric layer: Support defining a named derived metric (formula) that can be queried like a regular metric across dashboards and alerts. Higher reuse, but significantly more infrastructure.
- Client-side formula evaluation: Evaluate formulas in the widget rendering layer from raw query results. Simpler to ship, no backend changes, but limited to single time-bucket granularity and no alerting integration.
Recommendation
Extend the widget builder to support multi-query equations (option 1), consistent with existing Discover equation behavior. This provides the most direct path to the use case and aligns with ISWF-1927 for alerts.
Prior art
- Grafana, Datadog, and Honeycomb all support formula expressions across metric queries in dashboard panels as a first-class feature.
getsentry/sentry ISWF-1927 — same capability gap identified for Metric Alerts specifically.
Action taken on behalf of Richard Propst.
Summary
Dashboard widgets do not support computed expressions across metric queries. Users need to create derived metrics — such as
occurred / total = occurrence percentage— directly in dashboard widgets without relying on pre-aggregated custom metrics or workarounds in alerting.Current behavior
Dashboard widgets support individual metric queries (e.g. count of spans matching a filter) but have no way to compose two metric values into a formula. Users who want to display a ratio or percentage must either:
Gap
Dashboards are the primary surface for ongoing visibility into system health. Without formula support, any ratio-based KPI (occurrence rate, error rate, success rate) cannot be expressed as a first-class widget. Users must instrument derived values at the SDK level or maintain separate pipelines, increasing toil and reducing dashboard utility.
Options
a / b,a / (a + b) * 100), following the model already in place for transaction-based Discover widgets. Numerator and denominator queries are configured independently; the result drives the chart/number widget.Recommendation
Extend the widget builder to support multi-query equations (option 1), consistent with existing Discover equation behavior. This provides the most direct path to the use case and aligns with ISWF-1927 for alerts.
Prior art
getsentry/sentryISWF-1927 — same capability gap identified for Metric Alerts specifically.Action taken on behalf of Richard Propst.