Redis v3.2.1 發布，一個高性能的key-value數據庫
Redis 是完全開源免費的，遵守BSD協議，是一個高性能的key-value數據庫。
特點：
- Redis支持數據的持久化，可以將內存中的數據保持在磁盤中，重啟的時候可以再次加載進行使用。
- Redis不僅僅支持簡單的key-value類型的數據，同時還提供list，set，zset，hash等數據結構的存儲。
- Redis支持數據的備份，即master-slave模式的數據備份。
優勢：
- 性能極高 – Redis能讀的速度是110000次/s,寫的速度是81000次/s 。
- 豐富的數據類型 – Redis支持二進制案例的 Strings, Lists, Hashes, Sets 及 Ordered Sets 數據類型操作。
- 原子 – Redis的所有操作都是原子性的，同時Redis還支持對幾個操作全并后的原子性執行。
- 豐富的特性 – Redis還支持 publish/subscribe, 通知, key 過期等等特性。
更新日志
1. A critical bug in Sentinel was hopefully fixed. During the big 3.2
refactoring of Redis Sentinel, in order to implement connection sharing
to make Sentinel able to scale better (few Sentinels to monitor many
masters), a bug was introduced that mis-counted the number of pending
commands in the Redis link. This in turn resulted into an inability to talk
with certain Redis instances. A common result of this bug was the inability
of Redis Sentinel to reconfigure back the old master, after a failover,
when it is reachable again, as the slave of the new master. This was due
to the inability to talk with the old master at all.
2. BITFIELD bugs fixed.
3. GEO commands fixes on syntax errors and edge cases.
4. RESTORE now accepts dumps generated by older Redis versions.
5. Jemalloc now is really configured to save you memory, for a problem a
change in the jemalloc configuration did not really survived when the
3.2.0 release was finalized.
6. TTL and TYPE command no longer alter the last access time of a key, for
LRU evictions purposes. A new TOUCH command was introduced *just* to
update the access time of a key.
7. A bug was fixed in redis-cli, that connected to the instance running on the
port 6379 if there was one, regardless of what was specified.
8. TCP keep alive is now enabled by default. This should fix most ghost
connections problems without resulting in any practical change in otherwise
sane deployments.
9. A Sentinel crash that could happen during failovers was fixed.