Span
A single unit of work in a distributed trace, representing one operation (e.g., an HTTP call or database query). Spans are nested to form a trace tree.
What is Span?
A single unit of work in a distributed trace, representing one operation (e.g., an HTTP call or database query). Spans are nested to form a trace tree.
Span is a intermediate-level concept that sits in the Observability & Monitoring area of system design. Engineers reach for it whenever they need to reason about real-world trade-offs in that space — not just for textbook correctness, but because real production systems at companies like Netflix, Amazon, and Google make these decisions every day.
If you want to go deeper than this definition — with diagrams, code, and a quiz to lock it in — work through the "Span" lesson linked below. It walks through the why, the mechanism, the trade-offs, and how the giants actually use it in production.
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Full interactive lesson with diagrams, code examples, real-world references, and a quiz.
Open the Span lessonRelated lessons
Lessons that touch on Span as part of a larger topic.
Span IDs
Individual operations within a trace, each span is one unit of work with a start time, duration, and parent
intermediate · observability monitoring
NewSQL Databases
Distributed SQL databases that promise the scalability of NoSQL with the ACID guarantees of traditional SQL. CockroachDB, Google Spanner, and the NewSQL movement
intermediate · database types storage
Data Consistency Models
The full spectrum from eventual to strong, understand every model and when you need each one
advanced · consistency models
Global Tables
Fully replicated tables available in every region, low-latency reads worldwide with the trade-off of slower writes
intermediate · database types storage
See also
Related glossary terms you might want to look up next.
Distributed Tracing
Tracking a request as it flows through multiple services in a distributed system. Each service adds its trace, creating a full picture of the request journey.
Trace
The full end-to-end path of a request through a distributed system, composed of multiple spans. A trace shows which services were called, in what order, and how long each took.
Observability
The ability to understand a system's internal state from its external outputs. Built on three pillars: metrics, logs, and traces.