docs: public long getFirstExpiry() {
          final SQLiteDatabase db = getDb();
          if (db == null || !db.isOpen()) {
              return 0;
          }
          try {
              Cursor cursor = db.rawQuery("select min(" + COLUMN_EXPIRES + ") from " + TABLE, null);
              cursor.moveToFirst();
              long time = cursor.getLong(0);
              cursor.close();
              return time;
          } catch (Exception ex) {
              Log.e(IMapView.LOGTAG, "Unable to query for oldest tile", ex);
              catchException(ex);
          }
          return 0;
      }