[GUID] Flickr 的 Unique ID 產生方法 Ticket Servers

Flickr 的 Unique ID 是一個非常實際的解決問題方式，稱作 Ticket Servers 。
使用 MySQL 來達成 master -master 與 sharding 。

在使用一個table

CREATE TABLE `Tickets64` (
  `id` bigint(20) unsigned NOT NULL auto_increment,
  `stub` char(1) NOT NULL default '',
  PRIMARY KEY  (`id`),
  UNIQUE KEY `stub` (`stub`)
) ENGINE=MyISAM

SELECT * from Tickets64 returns a single row that looks something like:

+-------------------+------+
| id                | stub |
+-------------------+------+
| 72157623227190423 |    a |
+-------------------+------+ 

先插入一個ID值

使用

REPLACE INTO Tickets64 (stub) VALUES ('a');
SELECT LAST_INSERT_ID();

就會得到下一個ID

然後透過兩臺不同的設定奇偶數分開避免SPOF

TicketServer1:
auto-increment-increment = 2
auto-increment-offset = 1

TicketServer2:
auto-increment-increment = 2
auto-increment-offset = 2

Ticket Servers: Distributed Unique Primary Keys on the Cheap | code.flickr.com http://code.flickr.net/2010/02/08/ticket-servers-distributed-unique-primary-keys-on-the-cheap/