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zaishanfeng
V2EX  ›  MySQL

mysql sharding ,大家有什么好的方案吗?

  •  
  •   zaishanfeng · 2015-05-23 14:54:55 +08:00 · 4250 次点击
    这是一个创建于 3506 天前的主题,其中的信息可能已经有所发展或是发生改变。

    现在数据库层想做这样的方案,cluster+sharding,cluster方面资料挺多的,也基本上实现了,但是sharding方面好复杂,一种方案是业务层改变,另一种方案是加一层透明proxy,找了一下好像目前没有好用的proxy。业务层方面改又很费劲,面临以下问题:

    • Do I need to shard all of my tables or just the big tables?
    • How do I ensure my data is evenly distributed between shards?
    • How does sharding affect referential integrity constraints?
    • How do I use auto increment values and ensure unique values across all shards?
    • How do I perform joins between my sharded tables and non-sharded tables?
    • How do I run aggregrate queries that need data from multiple shards?
    • What if I need to add more shards later on or change the sharding strategy?
    • How do I perform the initial sharding of my existing data?
    • What about joins between shards and transactions involving multiple shards?
    • How do I ensure data is going to the correct shard?
    • How do I implement HA in a sharded environment?
    • How does sharding affect my backup/recovery procedures?

    请问大家都是怎么sharding的?最好是生产环境验证过的,谢谢

    3 条回复    2015-05-25 06:10:41 +08:00
    Actrace
        1
    Actrace  
       2015-05-23 16:16:45 +08:00
    分发的话,Haproxy不就够了吗..
    zaishanfeng
        2
    zaishanfeng  
    OP
       2015-05-23 16:28:09 +08:00
    @Actrace sharding 比如单表一亿条数据 分成十个子表 每个一千条
    siteshen
        3
    siteshen  
       2015-05-25 06:10:41 +08:00
    1. 用户产生的可能“超载”都需要 sharding
    2. sharding时指定个权重即可,刚开始3个sharding时,1:1:1,时隔半年增加3个sharding,1:1:1:5:5:5 即可(具体比例根据业务发展调整)
    3. 外键都得删掉,人工检查维护,当然完整性不能得到DB层保证
    4. ((timestamp -CONSTANTS) << 23) + (sharding_id << 10) + (auto_increment & (2<<10))(支持2^13个sharding)
    5. 避免join
    6. 每个sharding里aggregrate,代码里合并
    7. 一致性hash
    8. return sharding0 if id < 10^9
    9. WTF?
    10. 代码保证啊
    11. WTF?
    12. 和去掉外键一样,没法保证

    没在生产环境验证过,不谢。

    参考文献:
    [1] http://instagram-engineering.tumblr.com/post/10853187575/sharding-ids-at-instagram
    [2] http://media.postgresql.org/sfpug/instagram_sfpug.pdf
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