         try db.execute("CREATE TABLE IF NOT EXISTS grdb_migrations (identifier TEXT NOT NULL PRIMARY KEY)")
     }
     
-    private func appliedIdentifiers(_ db: Database) throws -> Set<String> {
+    private func appliedMigrations(_ db: Database) throws -> Set<String> {
         return try Set(String.fetchAll(db, "SELECT identifier FROM grdb_migrations"))
     }
     
     private func runMigrations(_ db: Database) throws {
-        let appliedIdentifiers = try self.appliedIdentifiers(db)
-        for migration in migrations where !appliedIdentifiers.contains(migration.identifier) {
+        let appliedMigrations = try self.appliedMigrations(db)
+        for migration in migrations where !appliedMigrations.contains(migration.identifier) {
             try migration.run(db)
         }
     }

        }
    }
    
    
    // MARK: - Non public
    

        GRDBPrecondition(prefixMigrations.last?.identifier == targetIdentifier, "undefined migration: \(String(reflecting: targetIdentifier))")
        
        // Subsequent migration must not be applied
        let appliedMigrations = try self.appliedMigrations(db)
        if prefixMigrations.count < migrations.count {
            let nextIdentifier = migrations[prefixMigrations.count].identifier
            GRDBPrecondition(!appliedMigrations.contains(nextIdentifier), "database is already migrated beyond migration \(String(reflecting: targetIdentifier))")
        }
        
        for migration in prefixMigrations where !appliedMigrations.contains(migration.identifier) {
            try migration.run(db)
        }
    }
