Comment by shanemhansen 3 days ago
To me traces (or maybe more specifically spans) are essentially a structured log with a unique ID and a reference to a parent ID.
Very open to have someone explain why I'm wrong or why they should be handled separately.
There are practical limitations mostly with backend analysis tools. OTel does not define a limit on how large a span is. It’s quite common in LLM Observability to capture full prompts and LLM responses as attributes on spans, for example.
> There are practical limitations mostly with backend analysis tools
Not just end-of-line analysis tools, but also initiating SDKs, and system agents, and intermediate middle-boxes -- really anything that needs to parse OTel.
Spec > SDK > Trace > Span limits: https://opentelemetry.io/docs/specs/otel/trace/sdk/#span-lim...
Spec > Common > Attribute limits: https://opentelemetry.io/docs/specs/otel/common/#attribute-l...
I know the spec says the default AttributeValueLengthLimit = infinity, but...
> It’s quite common in LLM Observability to capture full prompts and LLM responses as attributes on spans, for example.
...I'd love to learn about any OTel-compatible pipeline/system that supports attribute values of arbitrary size! because I've personally not seen anything that lets you get bigger than O(1MB).
Traces have a very specific data model, and corresponding limitations, which don't really accommodate log events/messages of arbitrary size. The access model for traces is also fundamentally different vs. that of logs.