bcquality/microsoft/knowledge/telemetry/keep-custom-dimension-schema-stable.md
Jesper Schulz-Wedde 2b5550c346
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Improve partner onboarding and documentation navigation (#174)
Lead with a complete plugin quick start and add task-oriented usage, troubleshooting, customization, and contribution guides. Preserve the broader plugin framing, correct conflicting contract guidance, support Agents folder reviews, and align repository validation. Convert existing sample references to clickable links without changing knowledge rules.

Co-authored-by: Jesper Schulz-Wedde <jesper.schulzwedde@microsoft.com>
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
2026-09-09 17:31:03 +02:00

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---
bc-version: [17..]
domain: telemetry
keywords: [customdimensions, dimension-key, schema, pascalcase, kql, breaking-change]
technologies: [al]
countries: [w1]
application-area: [all]
---
# Treat custom dimension keys as a stable telemetry schema
## Description
Business Central prefixes AL custom-dimension keys with `al` in Application Insights, so an AL key named `Result` becomes `alResult`. Microsoft guidance treats telemetry definitions as an API: changing or removing a custom dimension can break dashboards and alerts. PascalCase keys without spaces also compose cleanly in KQL; spaces force awkward bracket access and make queries harder to maintain.
## Best Practice
Choose stable PascalCase keys such as `Operation`, `Result`, and `RecordCount`. Keep the key set and meaning stable for a shipped event ID; add a new event ID or coordinate a schema migration when the meaning must change. Privacy guidance separately governs whether a dimension value may contain customer data.
See sample: [`keep-custom-dimension-schema-stable.good.al`](keep-custom-dimension-schema-stable.good.al).
## Anti Pattern
Keys such as `'order no'` or `'result_code'`, or renaming/removing a key while retaining the same shipped event ID. A naming-only issue is advisory; changing an existing event's schema is the material compatibility defect. New keys on a new event ID are not a breaking change.
See sample: [`keep-custom-dimension-schema-stable.bad.al`](keep-custom-dimension-schema-stable.bad.al).