A deprecation long overdue
OpenTelemetry is deprecating span events in favour of log records linked with trace context. Given just how many times we are asked "Should it be a span event or a log record?" by our customers, we are overjoyed at this streamlining in OpenTelemetry.
Span events exist because, in the beginning of the OpenTelemetry project, tackling logs as a separate signal felt like trying to bite off too much. But events like uncaught exceptions were still needed in the model, and so span events were introduced.
Now that logs in OpenTelemetry are stable in terms of specification, and implementation is complete or well underway in pretty much all SDKs, span events are no longer necessary. But, realistically, instrumentations generating span events will remain in use for a considerable time.
The new world, today
To help you with the transition, we have introduced an opt-in, per-dataset option to automatically convert span events into correlated log records during ingestion.
The resulting log records have the correct trace context on them, and "just work" the way you would expect. And in order for you to find out how many span events have been converted to logs, we add to the latter the dash0.span_event.converted = true log attribute.
That is, you do not need to modify your instrumentation, we just "fix your telemetry" for you. (But if you do want to fix your instrumentation, these agent skills we published a few weeks ago can help with the migration!)
Opting in to converting span events to logs will also hide the "Span events" column in your "All spans" Tracing view, but if you want, you can "bring it back" adding the Span event column to a custom view.
No impact on pricing
Span events and log records have always been equivalent in terms of pricing, as we saw this transition coming a long way.
The only effect on your bill is that the amount for "Spans and span events" will decrease by the same amount that "Logs" increases, based on how many span events you send.