--- a/pkg/scheduler/boot.go	Fri Dec 21 12:19:29 2018 +0100
+++ b/pkg/scheduler/boot.go	Fri Dec 21 13:04:46 2018 +0100
@@ -29,6 +29,10 @@
 SELECT id, username, kind, cron
 FROM waterway.import_configuration
 WHERE cron IS NOT NULL`
+
+	scheduledIDsSQL = `
+SELECT id from waterway.import_configuration
+WHERE username = $1 AND cron IS NOT NULL`
 )
 
 func init() { go boot() }
@@ -74,3 +78,28 @@
 		log.Printf("error: %v\n", err)
 	}
 }
+
+// ScheduledUserIDs returns the IDs with a schedule for a given user.
+func ScheduledUserIDs(
+	ctx context.Context,
+	conn *sql.Conn,
+	user string,
+) (map[int64]struct{}, error) {
+	ids := map[int64]struct{}{}
+	rows, err := conn.QueryContext(ctx, scheduledIDsSQL, user)
+	if err != nil {
+		return nil, nil
+	}
+	defer rows.Close()
+	for rows.Next() {
+		var id int64
+		if err := rows.Scan(&id); err != nil {
+			return nil, err
+		}
+		ids[id] = struct{}{}
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return ids, nil
+}