What is a Workflow Id?
A Workflow Id is a customizable, application-level identifier for a Workflow Execution that is unique to an Open Workflow Execution within a Namespace.
A Workflow Id is meant to be a business-process identifier such as customer identifier or order identifier.
A Workflow Id Reuse Policy can be used to manage whether a Workflow Id can be re-used. The Temporal Platform guarantees uniqueness of the Workflow Id within a Namespace based on the Workflow Id Reuse Policy.
It is not possible for a new Workflow Execution to spawn with the same Workflow Id as another Open Workflow Execution, regardless of the Workflow Id Reuse Policy.
An attempt to spawn a Workflow Execution with a Workflow Id that is the same as the Id of a currently Open Workflow Execution results in a Workflow execution already started error.
A Workflow Execution can be uniquely identified across all Namespaces by its Namespace, Workflow Id, and Run Id.