Each of a plurality of events associated with a workspace or stream are stored to a functional data structure. Each of the plurality of events includes at least an indication of when an operation in the workspace or stream occurred and who performed the operation. Nodes of a change set history tree corresponding to the events can be recursively identified until a node corresponding to a change set of interest is identified. Responsive to identifying the node corresponding to the change set of interest, the event corresponding to such node can be identified as an event that added the change set of interest to the workspace or stream. The indication of when the operation represented by the event occurred and who performed the operation can be retrieved from the subject event. The indication of when the operation represented by the event occurred, and who performed the operation, can be output.