Redis3.0.5学习笔记（一）基础入门
鲁春利的工作笔记，谁说程序员不能有文艺范？
官方网站：http://redis.io/
下载地址：http://redis.io/download
中文帮助：http://www.redis.cn/
Redis是一种面向“键/值”对数据类型的内存数据库，可以满足我们对海量数据的读写需求。
redis的键只能是字符串；
redis的值支持多种数据类型：
1：字符串 string
2：哈希 hash
3：字符串列表 list
4：字符串集合 set 不重复，无序
5：有序集合sorted set ，不重复，有序
6：HyperLogLog 结构（redis2.8.9版本之后才有,用来做基数统计的算法。）
特点：
高性能（Redis读的速度是11W次/s,写的速度是8.1W次/s）
原子性(保证数据的准确性)
持久存储（两种方式RDB/快照,AOF/日志）
主从结构（master-slave，负载均衡，高可用）
支持集群(3.0版本)
应用：应用在高并发和实时请求的场景。
新浪微博
hash：关注列表，粉丝列表
string：微博数，粉丝数（避免使用select count(*) from...）
sorted set：TopN，热门微博
还有github，stackoverflow等也用到了redis
下载版本：redis-3.0.5.tar.gz
将该tar文件拷贝到/usr/local目录下
# 解压 tar -xzv -f redis-3.0.5.tar.gz mv redis-3.0.5 redis3.0.5 cd redis3.0.5 # 编译安装 make make install # 单机版安装完成
会在/usr/local/bin目录下生成redis的执行命令
[root@nnode bin]# ll total 15468 -rw-r--r-- 1 root root 29 Nov 8 11:45 dump.rdb -rwxr-xr-x 1 root root 4587315 Nov 7 23:16 redis-benchmark -rwxr-xr-x 1 root root 22177 Nov 7 23:16 redis-check-aof -rwxr-xr-x 1 root root 45395 Nov 7 23:16 redis-check-dump -rwxr-xr-x 1 root root 4691466 Nov 7 23:16 redis-cli lrwxrwxrwx 1 root root 12 Nov 7 23:16 redis-sentinel -> redis-server -rwxr-xr-x 1 root root 6464797 Nov 7 23:16 redis-server
启动redis：
# /usr/local/bin目录已经存在于path路径中，可以直接调用该目录下的文件 [root@nnode redis3.0.5]# redis-server 14469:C 08 Nov 19:03:38.817 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf _._ _.-``__ ''-._ _.-`` `. `_. ''-._ Redis 3.0.5 (00000000/0) 64 bit .-`` .-```. ```\/ _.,_ ''-._ ( ' , .-` | `, ) Running in standalone mode |`-._`-...-` __...-.``-._|'` _.-'| Port: 6379 | `-._ `._ / _.-' | PID: 14469 `-._ `-._ `-./ _.-' _.-' |`-._`-._ `-.__.-' _.-'_.-'| | `-._`-._ _.-'_.-' | http://redis.io `-._ `-._`-.__.-'_.-' _.-' |`-._`-._ `-.__.-' _.-'_.-'| | `-._`-._ _.-'_.-' | `-._ `-._`-.__.-'_.-' _.-' `-._ `-.__.-' _.-' `-._ _.-' `-.__.-' 14469:M 08 Nov 19:03:38.855 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128. 14469:M 08 Nov 19:03:38.856 # Server started, Redis version 3.0.5 14469:M 08 Nov 19:03:38.856 # 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. 14469:M 08 Nov 19:03:38.856 # 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. 14469:M 08 Nov 19:03:38.890 * DB loaded from disk: 0.034 seconds 14469:M 08 Nov 19:03:38.890 * The server is now ready to accept connections on port 6379
此时redis是启在前台的，如果需要停止服务，只需要Ctrl+C即可：
^C14469:signal-handler (1446980678) Received SIGINT scheduling shutdown... 14469:M 08 Nov 19:04:38.334 # User requested shutdown... 14469:M 08 Nov 19:04:38.334 * Saving the final RDB snapshot before exiting. 14469:M 08 Nov 19:04:38.337 * DB saved on disk 14469:M 08 Nov 19:04:38.337 # Redis is now ready to exit, bye bye...
这种启动方式是非常不方便的，还是希望启动在后台，可以通过修改配置文件redis.conf来控制：
# 修改配置redis.conf： daemonize yes（后台运行） logfile /usr/local/redis3.0.5/logs/redis-log.out（日志文件，目录必须存在）
启动：
[root@nnode redis3.0.5]# redis-server /usr/local/redis3.0.5/redis.conf [root@nnode redis3.0.5]# ps -ef|grep redis root 14478 1 0 19:04 ? 00:00:00 redis-server *:6379 root 14482 11570 0 19:05 pts/0 00:00:00 grep redis [root@nnode redis3.0.5]#
客户端验证：
[root@nnode redis3.0.5]# redis-cli 127.0.0.1:6379> set name zs OK 127.0.0.1:6379> get name "zs" 127.0.0.1:6379> exit # 或者 redis-cli [-h 127.0.0.1][-p 6379]
关闭Redis：
[root@nnode redis3.0.5]# redis-cli 127.0.0.1:6379> shutdown not connected> exit [root@nnode redis3.0.5]# redis-cli shutdown
可以查看redis-server和redis-cli的帮助来了解其具体使用：
# redis-server [root@nnode redis3.0.5]# redis-server --help Usage: ./redis-server [/path/to/redis.conf] [options] ./redis-server - (read config from stdin) ./redis-server -v or --version ./redis-server -h or --help ./redis-server --test-memory <megabytes> Examples: ./redis-server (run the server with default conf) ./redis-server /etc/redis/6379.conf ./redis-server --port 7777 ./redis-server --port 7777 --slaveof 127.0.0.1 8888 ./redis-server /etc/myredis.conf --loglevel verbose Sentinel mode: ./redis-server /etc/sentinel.conf --sentinel # redis-cli [root@nnode redis3.0.5]# redis-cli --help redis-cli 3.0.5 Usage: redis-cli [OPTIONS] [cmd [arg [arg ...]]] -h <hostname> Server hostname (default: 127.0.0.1). -p <port> Server port (default: 6379). -s <socket> Server socket (overrides hostname and port). -a <password> Password to use when connecting to the server. -r <repeat> Execute specified command N times. -i <interval> When -r is used, waits <interval> seconds per command. It is possible to specify sub-second times like -i 0.1. -n <db> Database number. -x Read last argument from STDIN. -d <delimiter> Multi-bulk delimiter in for raw formatting (default: \n). -c Enable cluster mode (follow -ASK and -MOVED redirections). --raw Use raw formatting for replies (default when STDOUT is not a tty). --no-raw Force formatted output even when STDOUT is not a tty. --csv Output in CSV format. --stat Print rolling stats about server: mem, clients, ... --latency Enter a special mode continuously sampling latency. --latency-history Like --latency but tracking latency changes over time. Default time interval is 15 sec. Change it using -i. --latency-dist Shows latency as a spectrum, requires xterm 256 colors. Default time interval is 1 sec. Change it using -i. --lru-test <keys> Simulate a cache workload with an 80-20 distribution. --slave Simulate a slave showing commands received from the master. --rdb <filename> Transfer an RDB dump from remote server to local file. --pipe Transfer raw Redis protocol from stdin to server. --pipe-timeout <n> In --pipe mode, abort with error if after sending all data. no reply is received within <n> seconds. Default timeout: 30. Use 0 to wait forever. --bigkeys Sample Redis keys looking for big keys. --scan List all keys using the SCAN command. --pattern <pat> Useful with --scan to specify a SCAN pattern. --intrinsic-latency <sec> Run a test to measure intrinsic system latency. The test will run for the specified amount of seconds. --eval <file> Send an EVAL command using the Lua script at <file>. --help Output this help and exit. --version Output version and exit. Examples: cat /etc/passwd | redis-cli -x set mypasswd redis-cli get mypasswd redis-cli -r 100 lpush mylist x redis-cli -r 100 -i 1 info | grep used_memory_human: redis-cli --eval myscript.lua key1 key2 , arg1 arg2 arg3 redis-cli --scan --pattern '*:12345*' (Note: when using --eval the comma separates KEYS[] from ARGV[] items) When no command is given, redis-cli starts in interactive mode. Type "help" in interactive mode for information on available commands.
Redis默认支持16个数据库，其序号为0-15：
# 在redis.conf的配置文件中默认配置如下 # Set the number of databases. The default database is DB 0, you can select # a different one on a per-connection basis using SELECT <dbid> where # dbid is a number between 0 and 'databases'-1 databases 16
可以通过修改redis.conf中databases文件修改其支持的数据库个数；
序号是固定的，不支持自定义序号；
redis默认选中的是0号数据库；
SELECT 数字可以切换数据库；
多个数据库之间不是完全隔离，flushall能够清理所有数据。
[root@nnode redis3.0.5]# redis-cli 127.0.0.1:6379> get name (nil) 127.0.0.1:6379> set name zs OK 127.0.0.1:6379> get name "zs" 127.0.0.1:6379> select 1 OK 127.0.0.1:6379[1]> get name (nil) 127.0.0.1:6379[1]> set name li OK 127.0.0.1:6379[1]> get name "li" 127.0.0.1:6379[1]> select 0 OK 127.0.0.1:6379> get name "zs" 127.0.0.1:6379> select 16 (error) ERR invalid DB index 127.0.0.1:6379> flushall OK 127.0.0.1:6379> select 0 OK 127.0.0.1:6379> get name (nil) 127.0.0.1:6379> exit # flushall之后数据库0和1的值都被清理了。 [root@nnode redis3.0.5]#