GRAYLOG - Chapter 4, Exercise 2 Solution
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requestId vs. correlationId: A Difference in Scope

PROBLEM
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Explain, using this chapter's own material, the real difference in
scope between requestId and correlationId - which one is broader, and
what real example does this chapter give for when the broader one is
actually needed?

SOLUTION
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This chapter established that requestId (along with restRequestId and
messageRequestId) correlates log lines produced while handling ONE
single HTTP request. correlationId operates "one level up" from that -
it correlates one item or job as it moves through CROSS-SERVICE steps,
which can span multiple separate requests, not just one.

correlationId is therefore the BROADER of the two fields - a single job
tracked by one correlationId could genuinely involve several different
requestId values along the way, one per request-shaped step.

The chapter's own real example of when the broader field is needed:
a Flux pipeline run that touches several distinct services in sequence
- correlationId is what ties that whole multi-step job together, where
requestId alone would only show one piece of it.

ANSWER: correlationId is broader than requestId - it correlates a whole
cross-service job (potentially spanning multiple requests), while
requestId only correlates the log lines from a single HTTP request. The
chapter's own real example for needing the broader field is a Flux
pipeline run spanning several services.

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WHY THIS WORKS AS AN ANSWER

This is a direct restatement of the chapter's own explicit scope
comparison, using its own real Flux example rather than inventing a new
one. The practical lesson: if a requestId-scoped search feels like it's
only showing part of the picture for a multi-step job, correlationId is
the field to reach for next, since it operates at genuinely the right
scope for that broader question.