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I am developing a mobile application for field technicians that must support full offline functionality for data entry. The technicians create work orders and customer reports in areas with no cellular service. When they return to a connected area, the app must synchronize all local changes with the central server. My main concern is preventing primary key conflicts when multiple technicians upload their reports simultaneously. How can I ensure that an ID generated on a technician's phone will never conflict with an ID generated by another phone or the central database?