Extracting Span ID from Legacy ID

[Dmitry-Matveev]

As part of our move towards W3C correlation standard, Application Insights will start transforming legacy correlation IDs matching certain pattern into W3C span IDs for Request and Dependency telemetry items. You can still find the original ID in the custom property ai_legacyRequestId.

If Request or Dependency ID matches |operationId.spanId. pattern, then spanId is used as an ID instead. Similar logic applies to Parent ID field on all items.

If Request ID or Dependency ID is changed like that, then transformation rule adds ai_legacyRequestId custom dimension with the original ID value (|traceId.spanId.)

The expected timeline of the change - EOM November.