Mastering Distributed Tracing

Span tags versus logs

Let's expand a couple more spans.

Figure 2.10: Two more spans expanded to show a variety of tags and logs. Each span also contains a section called "Process" that also looks like a collection of tags. The process tags describe the application that was producing the tracing record, rather than an individual span.

In the customer span, we can see a tag http.url that shows that the request at the /customer endpoint had a parameter customer=123, as well as two logs narrating the execution during that span. In the mysql span, we see an sql.query tag showing the exact SQL query that was executed: SELECT * FROM customer WHERE customer_id=123 ...