python - 重複エラー

Question

次のモジュールを使用して一意の ID を生成しています。しかし、毎日IntegrityError: (1062, "Duplicate entry '122830001' for key 'PRIMARY'")最初のローン ID がスローされます。

問題の原因がわかりません。助けてください？

def generate_loanid(leadid='0', counter=0):
    """ Locks the customer_loanid table retrieves maximum loanid from it.
        Generates a new loanid and puts it back in the table.
        Returns the new loanid.
    """
    def gen_id(max_loanid=0, count=0):
        """
        Increments the counter if an id exists for the day.
        Else resets the counter and creates a fresh one.
        """
        timestamp_now = time.localtime()
        if max_loanid:
            logger.debug("""Current Maximum Loan id :
                        (Year(YY)+Julian Day(DDD)+Counter(CCCC) %d,
                        Current timestamp : %s""" %(max_loanid, timestamp_now))
            julian_day = (max_loanid/10000) % 1000
            if julian_day == timestamp_now[7]:
                count = max_loanid % 10000
        return (str(timestamp_now[0])[2:] +
                str(timestamp_now[7]).rjust(3, '0') +
                str(count+1).rjust(4, '0')
                )

    logger.debug("Leadid:%s - Counter:%s"%(leadid, counter))
    db_obj = dbLis(pooling=False)
    try:
        try:
            db_obj.query("lock tables customer_loanid write")
            max_loanid = db_obj.query("select max(loanid) as loanid from customer_loanid")
            curr_loanid = gen_id(max_loanid = max_loanid.__len__() and max_loanid[0].loanid)
            db_obj.insert('customer_loanid', loanid=curr_loanid)
        except (MySQLdb.IntegrityError,MySQLdb.OperationalError):
            logger.warning(traceback.format_exc())
            #There is no logical backing for this piece of code.
            if counter < 3:
                db_obj.query("unlock tables")
                return generate_loanid(counter=counter+1)
            else:
                raise
    finally:
        try:
            db_obj.query("unlock tables")
            logger.debug("Unlocked All Tables")
            db_obj.ctx.db.close()
        except MySQLdb.OperationalError:
            logger.info("Table unlocked already")
            logger.debug(traceback.format_exc())
    logger.info("Generated Loanid : %s"%(curr_loanid))
    return curr_loanid

テーブル構造:

CREATE TABLE `customer_loanid` (
  `loanid` int(15) NOT NULL DEFAULT '0',
  PRIMARY KEY (`loanid`)
)