Understanding Execution Traces

Read parent and child operations as one request-linked execution hierarchy.

The HTTP server span is the root. Framework middleware, handlers, database queries, Redis commands, and outgoing HTTP operations become child spans when they execute in the same OpenTelemetry context.

Read the hierarchy

Start with total request duration, then locate the longest child operation. A child database or outbound HTTP span can explain a slow handler without relying on log timestamps.

Common shapes

HTTP request → Express middleware → route handler → MongoDB query
HTTP request → Nest handler → pg query → outgoing fetch
HTTP request → handler → ioredis command with error status

Durations are stored with each span. Errors mark the relevant span and update the trace summary.