Span attribute keys have unspecified case sensitivity

[jorisgeer]

What needs to be changed? Describe the update that is required.

The documentation does not state whether span attribute keys are case sensitive

What is the name + path of the page that needs changed? The relative path
and page title where you found a problem.

concepts/signals/traces/#attributes - Span Attributes

Additional context: anything else you can think about that would be helpful.

If attribute keys are meant to be case sensitive - in line with most common programming languages - , any vendor that treats them case insensitive will cause a collision. The other way around an intentional case variation will result in a mismatch.

[svrnm]

Thank you for raising this issue. This needs to be clarified (and probably is?) via the specification, then we can apply the change accordingly. I am not 100% sure if this is specified.

@open-telemetry/specs-approvers can someone take a look? I found #504 but I might miss some conclusion on this question in the spec.

[pyohannes]

Seems there's no explicit mention of this in the spec, but it's implicitly assumed that attribute names are case-sensitive.

Attributes are defined as Unicode sequences:

Every name MUST be a valid Unicode sequence.

And different Unicode sequences would be different attribute names.

It might be worth pointing this out explicitly.

[tigrannajaryan]

Perhaps clarify somewhere here: https://github.com/open-telemetry/opentelemetry-specification/tree/main/specification/common#attribute-collections

[chalin]

@svrnm et al.: should this issue be transferred to the spec repo?

[tigrannajaryan]

@svrnm et al.: should this issue be transferred to the spec repo?

Yes, I think it belongs to spec. Moved.

[tigrannajaryan]

We need someone to submit a PR to clarify this in the spec.