Redis介绍及入门安装及使用
什么是Redis
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, geospatial indexes with radius queries and streams. Redis has built-in replication, Lua scripting, LRU eviction, transactions and different levels of on-disk persistence, and provides high availability via Redis Sentinel and automatic partitioning with Redis Cluster。
根据Redis的官网介绍，我们可以得知Redis有以下功能及特性：
- Redis是一个开源的、基于BSD协议的内存数据结构存储，可以用来当做数据库、缓存、消息代理。
- 支持的数据格式包括：strings、hashes、lists、sets、sorted sets with range queries、bitmaps, hyperloglogs、geospatial indexes with radius queries 、streams。
- Redis本身提供复制、Lua脚本、LRU清除、事务、及不同级别的持久机制，通过Sentinel和Cluster来保证高可用性。
为什么要选择Redis
- 性能优异，Redis官方验证了在不同CPU下的Redis性能，感兴趣的同学请移步，https://redis.io/topics/benchmarks ，每秒10w+的读写操作是完全是小菜一碟，当然在实际中因为服服务器的CPU/环境会有些许出入，但足以应对觉得大多数的复杂应用场景。
- 支持复杂的数据结构，除了常用的KEY -Value之外，还支持其他多种复杂的数据结构，比如Set 、Lists、bitmaps、hyperloglogs 、 geospatial 、stream。
- 提供了持久化的功能，方便快速恢复数据。
- 支持读写分离、主从复制、哨兵模式、集群模式，保证高可用。
- 对存储的Value大小没有内容限制。方便存储较大的数据。
安装Redis
官网最新稳定的版本为：[Redis 5.0.6 is the latest stable version]:http://download.redis.io/releases/redis-5.0.6.tar.gz 。
Redis的安装
$ wget http://download.redis.io/releases/redis-5.0.6.tar.gz
$ tar xzf redis-5.0.6.tar.gz
$ cd redis-5.0.6
$ make
如果在执行make指令时出现如下错误：
/bin/sh: cc: command not found
make[1]: *** [adlist.o] Error 127
make[1]: Leaving directory `/opt/software/redis/redis-5.0.6/src'
make: *** [all] Error 2
说明没有安装gcc,因为Redis是C实现的，所以需要安装gcc来进行编译。
安装gcc指令：
yum install gcc
安装完成后执行以下操作：
# 删除上次安装的Redis目录及子目录
$ rm -rf redis-5.0.6
# 重新解压和编译
$ tar xzf redis-5.0.6.tar.gz
$ cd redis-5.0.6
$ make
启动服务端
# 启动服务端
[enjoyitlife@localhost redis-5.0.6]$ src/redis-server
# 启动成功会显示如下信息
[enjoyitlife@localhost redis-5.0.6]$ src/redis-server
11872:C 20 Nov 2019 07:13:57.586 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
11872:C 20 Nov 2019 07:13:57.586 # Redis version=5.0.6, bits=64, commit=00000000, modified=0, pid=11872, just started
11872:C 20 Nov 2019 07:13:57.586 # Warning: no config file specified, using the default config. In order to specify a config file use src/redis-server /path/to/redis.conf
11872:M 20 Nov 2019 07:13:57.589 # You requested maxclients of 10000 requiring at least 10032 max file descriptors.
11872:M 20 Nov 2019 07:13:57.590 # Server can't set maximum open files to 10032 because of OS error: Operation not permitted.
11872:M 20 Nov 2019 07:13:57.590 # Current maximum open files is 4096. maxclients has been reduced to 4064 to compensate for low ulimit. If you need higher maxclients increase 'ulimit -n'.
_._
_.-``__ ''-._
_.-`` `. `_. ''-._ Redis 5.0.6 (00000000/0) 64 bit
.-`` .-```. ```\/ _.,_ ''-._
( ' , .-` | `, ) Running in standalone mode
|`-._`-...-` __...-.``-._|'` _.-'| Port: 6379
| `-._ `._ / _.-' | PID: 11872
`-._ `-._ `-./ _.-' _.-'
|`-._`-._ `-.__.-' _.-'_.-'|
| `-._`-._ _.-'_.-' | http://redis.io
`-._ `-._`-.__.-'_.-' _.-'
|`-._`-._ `-.__.-' _.-'_.-'|
| `-._`-._ _.-'_.-' |
`-._ `-._`-.__.-'_.-' _.-'
`-._ `-.__.-' _.-'
`-._ _.-'
`-.__.-'
11872:M 20 Nov 2019 07:13:57.594 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
11872:M 20 Nov 2019 07:13:57.595 # Server initialized
11872:M 20 Nov 2019 07:13:57.595 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
11872:M 20 Nov 2019 07:13:57.595 # WARNING you have Transparent Huge Pages (THP) support enabled in your kernel. This will create latency and memory usage issues with Redis. To fix this issue run the command 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' as root, and add it to your /etc/rc.local in order to retain the setting after a reboot. Redis must be restarted after THP is disabled.
11872:M 20 Nov 2019 07:13:57.595 * Ready to accept connections
客户端连接
# 新开一个Shell 窗口
[enjoyitlife@localhost ~]$ cd /opt/software/redis/redis-5.0.6
[enjoyitlife@localhost redis-5.0.6]$ src/redis-cli
# 表示连接成功
127.0.0.1:6379>
命令测试
127.0.0.1:6379> set name enjoyitlife
OK
127.0.0.1:6379> get name
"enjoyitlife"
127.0.0.1:6379>
设置Redis后台运行
# 修改redis.conf 中 daemonize no 改成 yes
daemonize yes
# 可以先将文件改下名，然后在启动的时候 以指定的文件启动
[enjoyitlife@localhost redis-5.0.6]$ cp redis.conf redis6379.conf
[enjoyitlife@localhost redis-5.0.6]$ src/redis-server redis6379.conf
# 此时就不会出现Redis的Logo图片了，而是如下说明， 表明后台启动Redis成功
[zpenjoy@localhost redis-5.0.4]$ src/redis-server redis6379.conf
11920:C 20 Nov 2019 07:21:21.021 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
11920:C 20 Nov 2019 07:21:21.022 # Redis version=5.0.6, bits=64, commit=00000000, modified=0, pid=11920, just started
11920:C 20 Nov 2019 07:21:21.022 # Configuration loaded
停止Redis服务
# 可以通过关闭进程的方式 强制关闭 不建议使用该方式
[enjoyitlife@localhost ~]$ ps -ef|grep redis
[enjoyitlife@localhost redis-5.0.6]$ ps -ef|grep redis
enjoyit+ 11921 1 0 07:21 ? 00:00:00 src/redis-server 127.0.0.1:6379
enjoyit+ 11929 11898 0 07:23 pts/1 00:00:00 src/redis-cli
enjoyit+ 11956 11933 0 07:25 pts/0 00:00:00 grep --color=auto redis
[enjoyitlife@localhost redis-5.0.6]$ kill -9 11921
# 推荐方式
./src/redis-cli shutdown
好了，Redis基本介绍及安装就介绍到这里了，谢谢阅读。