---
title: "Correlation is powerful, but it isn't automatic | Grafana Labs"
description: "Define exemplar plainly; cross-signal correlation needs prerequisites and isn't a switch that's on by default."
---

> For a curated documentation index, see [llms.txt](/llms.txt). For the complete documentation index, see [llms-full.txt](/llms-full.txt).

## Correlation is powerful, but it isn’t automatic

A slow trace often raises a follow-up question: which metric alerted you to it, or what the logs for this exact request say. Jumping from one signal to another for the same request is called **correlation**, and it’s one of the most useful things you can do once you can read a trace.

These links run in both directions, and each one is its own clickable jump. A metric chart can carry a link that takes you straight to a representative trace behind a spike; that link is called an **exemplar**. In the same way, a log line can carry a link to the trace for that exact request, so you can open a log and jump straight to the trace that produced it.

## It needs prerequisites

Correlation works once it’s set up, but the jumps don’t happen on their own. The jump from a log to its trace, for example, needs a few pieces in place first:

- **Trace IDs travel with your telemetry**: your logs carry the trace ID of the request they belong to, so a log line can be tied back to its trace.
- **A link is configured**: a Grafana data source setting, called a **derived field**, turns that trace ID in the log into a clickable link to the trace.
- **The target exists**: the trace data source you’re linking to is connected in Grafana.

The diagram shows both jumps landing on the trace, with the log-to-trace jump resting on the three prerequisites above.

[Two correlation jumps that both land on a trace: an exemplar links a metric to the trace, and a derived field links a log line to the trace. The log-to-trace jump depends on three prerequisites: the trace ID travels with telemetry, a derived field is configured, and the target data source exists](correlation-jumps.svg "Two correlation jumps that both land on a trace: an exemplar links a metric to the trace, and a derived field links a log line to the trace. The log-to-trace jump depends on three prerequisites: the trace ID travels with telemetry, a derived field is configured, and the target data source exists")

When a piece is missing, the jump quietly does nothing. So treat cross-signal correlation as a payoff you set up, not a switch that’s on by default. Wiring it up is part of the separate setup journey.