Can you give an example of when local keys are used in a database or system?

Local keys in a database or system are used when it is necessary to ensure the uniqueness of a record within a specific context or group, rather than across the entire database. For example, in a Flutter application with a local database (such as SQLite), local keys can be used to identify elements within a particular user or category.

Example: In a notes app, each user has their own notes, and each note has a unique local key (for example, id), unique only within that user, but not globally across the entire database. This helps avoid conflicts during synchronization or offline data handling.

class Note {
  final int localId; // unique only for a specific user
  final String content;
  
  Note(this.localId, this.content);
}

Thus, local keys help structure and manage data within a limited context.