Redis Learning

应用场景：
redis 适用于小而热的数据

• Redis应用场景
• Redis作者谈Redis应用场景
  我们在应用redis的场景是　缓存
  将收到的post报文缓存下，然后批量插入redshift

github上的scala版redis　client
官方推荐了好几款开源的scala 版客户端，都不知道选哪个比较好了，应该迅速读一遍scala 并发编程

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Redis is an open source(BSD Licensed),in-memory data structure store,
used as a database,
cache,
and message broker.
It supports data structures such as strings,hashes,lists,sets,sorted sets with range queries,bitmaps,hyperloglogs and geospatial indexes with radius queries.
build-in:

• replication
• Lua scripting
• LRU eviction
• transaction
• different levels of on-disk persistence
• provides high availability via Redis Sentinel and automatic partitioning with Redis Cluster.

You can run atomic operations on these types, like appending to a string; incrementing the value in a hash; pushing an element to a list; computing set intersection, union and difference; or getting the member with highest ranking in a sorted set.

in-memory dataset:

In order to achieve its outstanding performance, Redis works with an in-memory dataset. Depending on your use case, you can persist it either by dumping the dataset to disk every once in a while, or by appending each command to a log. Persistence can be optionally disabled, if you just need a feature-rich, networked, in-memory cache.

no-blocking replication:

Redis also supports trivial-to-setup master-slave asynchronous replication, with very fast non-blocking first synchronization, auto-reconnection with partial resynchronization on net split.

transcation数据库事务
彻底搞懂事务

6379-为何Redis选择它作为默认端口号？
redis 使用服务器端／客户端架构的数据库架构
通过client去连接redis服务端

• 我们可以通过redis-cli去连接redis数据库，这是学习测试redis最好的方法，这时redis-cli就是一个client

• 之前连接关系型数据库一般都是通过JDBC的方式连接的，这个redis是怎么连接上去的我暂时还没有搞清楚，官方推荐了很多类似与sdk的工具库，使用这些库可以很方便的连接redis，

• redis 持久化
  有两种方式做持久化，其一是RDB，定期备份数据库的状态；其二是AOF，记录数据库的相关命令
  优先使用AOF方式

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使用list来存储数据，LPUSH mylist "1"
// BRPOP mylist 0 取出最先放入的元素，
每分钟生成一个key,同步数据只处理之前的key里面的数据
做一个事务，保证该元素处理的原子性
因为BRPOP 只能取出最后一个元素，所以应该使用BPOPLPUSH

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