Systems, methods, and computer-readable storage media for ensuring data consistency and concurrency for globally unique identifiers (GUIDs) and associated content items via locking. A content management system configured to practice the method can receive, from a client device, a request to perform a content item operation in a storage environment that affects a GUID. Then the content management system can acquire a first mutex for a namespace associated with the content item operation, such as an application-level lock, and acquire a second mutex for the GUID, such as a row-level lock in a database table. After acquiring the locks, the content management system can perform the content item operation according the request, and update the GUID based on the content item operation. Then the content management system can release the mutexes and provide a confirmation to the client device in response to the request.