In what situations are global keys used in databases or data storage systems?

Global keys in databases and data storage systems are used for the unique identification of records across the entire system or even between different systems. Main use cases:

• Ensuring uniqueness: when it is necessary to guarantee that a record identifier is unique across all tables or databases (e.g., UUID).

• Replication and data synchronization: when exchanging data between different databases or services, global keys help match and merge records.

• Distributed systems: in distributed databases where there is no single center, global keys help avoid identifier conflicts.

• Caching and cross-service interaction: global keys simplify data lookup and linking between different services.

For example, in Flutter, when working with local databases (such as SQLite) or cloud services (Firebase), global keys help uniquely identify objects, especially when data is synchronized between devices.