Technical Glossary

• Span: A named, timed operation representing a single unit of work within a trace.
• Trace: A Directed Acyclic Graph (DAG) of spans representing end-to-end request execution across microservices.
• Critical Path: The longest sequential chain of dependent operations in a trace DAG that directly dictated total request latency.
• W3C TraceContext: The standard specification for distributed context propagation via traceparent and tracestate HTTP headers.
• OTLP: OpenTelemetry Protocol, the vendor-neutral telemetry transport standard over gRPC and HTTP.
• Head Sampling: A sampling policy evaluated at the initial gateway before request processing occurs.
• Tail Sampling: A sampling policy evaluated after request completion, retaining traces based on errors or latency anomalies.
• Columnar Storage: A database architecture storing data by column rather than row, enabling extreme compression and ultra-fast aggregations.
• Clock Skew: The time divergence between independent physical server clocks across a distributed cluster.