Understand this story
On October 26, 2026, Marcelo Trylesinski wrote an article arguing that logs are not enough to replace traces. The Pydantic Logfire article points out that logs only record what happened at a certain point in time, whereas spans carry a trace ID, span ID, parent span ID, and start and end times, which can show which operations belong to the same request, who called whom, and where time is spent. The article uses three concurrent checkout requests to demonstrate: logs alone cannot determine which user took about 2 seconds; even after adding a request ID, timestamps still need to be manually subtracted; and structured logs are also insufficient when the same operation is retried or an operation is not completed. This argument is currently published as an official Pydantic AI article, and there have been no subsequent developments.
AI-generated from public reports
Latest development · Report
The difference between logs and traces: why logs alone are not enoughDevelopments
1 confirmed developments
Marcelo Trylesinski argues in writing that logs are not enough to replace traces
Source:English text is being prepared.
Reports and discussion timeline
Browse reports and discussion by time. Their evidence levels remain distinct.
Oct 26
Pydantic AI official articleFirst-party
The difference between logs and traces: why logs alone are not enough
The Pydantic Logfire article points out that logs only record what happened at a certain point in time, whereas spans carry a trace ID, span ID, parent span ID, and start and end times, and can show which operations belong to the same request, who called whom, and where time is spent. The article uses three concurrent checkout requests to demonstrate: logs alone cannot determine which user took about 2 seconds, and even after adding a request ID, timestamps still have to be subtracted manually; moreover, when the same operation is retried or an operation is not completed, structured logs are also insufficient.