问题描述
- 用例是使用Redis作为MySQL的本地缓存
- MySQL 中的数据格式是:一个主键和几个其他字段.不会有db的跨表查询
- Redis key 是 MySQL 中的主键，value 是包含 MySQL 中其他字段的 hash
- 断电时，数据丢失少于一分钟是可以接受的.
我的解决方案是:
- Redis 写入 AOF 文件，某些进程会监视此文件并将更新的数据同步到 MySQL
- Hack Redis 将 AOF 写在多个文件中，就像 MySQL binlog 一样
- 数据接口只会通过Redis读写
这个解决方案好吗?
完成这项工作的最佳策略是什么?
Is this solution OK?
And what's the best strategy to do this job?
推荐答案
你不需要破解任何东西 ;)
You don't need to hack anything ;)
我不完全确定您为什么需要 mysql 上的数据.如果我知道，也许会有更合适的答案.在任何情况下，作为通用答案，您可以使用 redis 键空间通知
I am not entirely sure why you need the data on mysql. If I knew, maybe there would be a more suitable answer. In any case, as a generic answer you can use redis keyspace notifications
您可以在您的密钥上订阅命令 HSET、HMSET、HDEL 和 DEL，这样每次删除密钥或设置或删除哈希值时您都会收到通知.
You could subscribe to the commands HSET, HMSET, HDEL and DEL on your keys, so you would get a notification everytime a key is deleted or a hash value is set or removed.
请注意，如果您错过任何通知，就会出现不一致的情况.因此，偶尔您可以使用 SCAN 命令查看所有密钥并检查 mysql 是否需要更新.
Note if you miss any notification you would have an inconsistency. So once in a while you could just use the SCAN command to go through all your keys and check on mysql if they need to be updated.
另一种策略可能是维护两个独立的结构.一个是带有值的散列，另一个是按更新时间戳排序的所有值的 ZSET.保持这两种结构最新的最好方法是编写两个或三个 lua 脚本(插入/更新和删除)，它们将原子地操作散列和 zset.
Another strategy could be maintaining two separate structures. One would be the hash with the values, and the other would be a ZSET of all the values sorted by timestamp of update. The best way to keep both structures up to date would be to write two or three lua scripts (insert/update and delete) that would operate on the hash and the zset atomically.
然后，您可以定期查询 ZSET 中时间戳高于上次同步操作的元素，获取所有更新的键(它将包括已删除的键，除非您想为这些键保留第二个 ZSET)然后只需通过键检索所有元素并同步到mysql.
Then you can just periodically query the ZSET for the elements with a timestamp higher than your last sync operation, get all the keys that were updated (it would include deleted keys, unless you want to keep a second ZSET exclusively for those) and then just retrieve all the elements by key and sync to mysql.
希望它对你有用！
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