There’s two ways in which traces make it to Jaeger. Both of them ignore lazy tags.

1. We can generate a jaeger json from a recording. The json can then be dragged-and-dropped into Jaeger, which renders the trace. This happens here:
   

   cockroach/pkg/util/tracing/tracingpb/recording.go

   Line 368 in 67ff407

   func (r Recording) ToJaegerJSON(stmt, comment, nodeStr string) (string, error) {

2. You can ask crdb to trace everything and export all traces to Jaeger.

Case 1) I think needs a bit of code to render the lazy tags and add them to the json.
Case 2) is conceptually tricky, although in practice I think there’s only one thing we can do. The point of the lazy tags is that they’re only rendered on demand. OpenTelemetry has no interface to express such “demand”. What we can do is render the lazy tags just before the otel span is finished, and add the stringified version to the otel span as an otel tag. That would happen here:

Jira issue: CRDB-18074