public boolean removeByKey(String tableName, String key) throws DBUnavailabilityException,
            DataBaseRequestException, DataBaseTableException {
        if (key == null) {
            throw new DataBaseRequestException("key shouldn't be null");
        }

        String firstCharAtName = key.substring(0, 1);
        DataBase db = getDataBaseByKey(firstCharAtName);
        return db.removeByKey(tableName, key);
    }