Namespace

A namespace is the administrative isolation boundary for everything in a Temporal cluster: workflows, schedules, search attributes, archival, replication.

Aspect	Detail
Identity	Unique name + opaque NamespaceID (UUID).
Settings	Retention period, archival URI, active cluster, replication targets, search-attribute mapping.
Persistence	One row in namespaces (and namespace_metadata); see common/persistence/metadata_manager.go.
Cache	Per-process namespace cache: common/namespace/registry.go.
Frontend handlers	service/frontend/namespace_handler.go.
Async deletion	service/worker/deletenamespace/.

Lookup path

Almost every gRPC handler resolves a namespace name → ID early in its processing. The namespace cache is read on every call; cache misses go to the metadata manager. The cache refreshes via long-polling against the metadata table so updates from any cluster propagate within seconds.

Replication

A namespace's ActiveClusterName and ReplicationConfig together determine multi-cluster behaviour. Updates to those fields are themselves replicated.

Where to read more

• Features → Namespaces and multi-cluster
• Frontend service
• Replication