Logid

Logid, log ID, or log-id refers to a unique identifier assigned to a log entry or to a request as it traverses a system. It is used to correlate related events across services, hosts, and time, supporting search, filtering, and tracing in logging and monitoring pipelines.

In practice, logids take different forms. Some systems use numeric sequences or auto-incremented counters per source. Others adopt global identifiers such as UUIDs (RFC 4122) or compact sortable IDs like ULIDs. Some frameworks propagate a per-request identifier through the call chain, attaching the same logid to all log messages generated during handling of that request.

Relation to other concepts: a logid is often distinct from but related to trace IDs and span IDs used by distributed tracing. A logid may serve as a lightweight correlation key when full tracing is not implemented, or as a means to link log entries with traces.

Generation and management: logids can be generated client-side or server-side. They should be globally unique in distributed deployments to avoid collisions. Some systems include the logid in the log line format to speed up indexing in centralized log stores.

Considerations: length, privacy, entropy, and performance. Long or sensitive identifiers may raise privacy concerns or storage overhead. Consistency across an organization is important to enable effective searching.