【读书笔记】Redis实战 中文.pdf

Redis 的作者 antirez 曾笑称 Redis 为一个数据结构服务器(data structures server),我认为这 是一个非常准确的表述,
Redis 的所有功能就是将数据以其固有的几种结构来保存,并提供 给用户操作这几种结构的接口。

$ redis-cli -h 10.117.146.16 -p 6379
10.117.146.16:6379> set testName shanghai
OK
10.117.146.16:6379> get testName
"shanghai"
10.117.146.16:6379> set testName zhongguo
OK
10.117.146.16:6379> get testName
"zhongguo"
10.117.146.16:6379> setnx testName beijing
(integer) 0
10.117.146.16:6379> get testName
"zhongguo"
10.117.146.16:6379> setex testName 3 shanghai
OK
10.117.146.16:6379> get testName
"shanghai"
10.117.146.16:6379> get testName
(nil)
10.117.146.16:6379> set testName zhongguo
OK
10.117.146.16:6379> get testName
"zhongguo"
10.117.146.16:6379> setrange testName 5 d
(integer) 8
10.117.146.16:6379> get testName
"zhongduo"

10.117.146.16:6379> mset k1 v1 k2 v2
OK
10.117.146.16:6379> get k1
"v1"
10.117.146.16:6379> get k2
"v2"

msetnx一个不成功，就所有不成功

10.117.146.16:6379> mset k3 v3 k2 v2
OK
10.117.146.16:6379> msetnx k4 v4 k3 v3
(integer) 0
10.117.146.16:6379> get k3
"v3"
10.117.146.16:6379> get k4
(nil)

getset不存在的，返回nil，但是能够设置成功

10.117.146.16:6379> getset k5 v5
(nil)
10.117.146.16:6379> get k5
"v5"

getrange和mget：

10.117.146.16:6379> get testName
"zhongduo"
10.117.146.16:6379> getrange testName 0 2
"zho"
10.117.146.16:6379> getrange testName -3 -1
"duo"
10.117.146.16:6379> getrange testName 6
(error) ERR wrong number of arguments for ‘getrange‘ command
10.117.146.16:6379> getrange testName 6 100
"uo"
10.117.146.16:6379> mget k1 k2 k6
1) "v1"
2) "v2"
3) (nil)

incr命令：
10.117.146.16:6379> set age 20
OK
10.117.146.16:6379> incr age
(integer) 21
10.117.146.16:6379> get age
"21"

10.117.146.16:6379> get age
"21"
10.117.146.16:6379> incrby age 5
(integer) 26
10.117.146.16:6379> get age
"26"
10.117.146.16:6379> incrby age2 5
(integer) 5
10.117.146.16:6379> get age2
"5"

10.117.146.16:6379> decr age2
(integer) 4
10.117.146.16:6379> decrby age2 3
(integer) 1

decrby可以用incrby 负数来进行

10.117.146.16:6379> append testName .com
(integer) 12
10.117.146.16:6379> get testName
"zhongduo.com"
10.117.146.16:6379> strlen testName
(integer) 12

Redishash是一个string类型的field和value的映射表.它的添加、删除操作都是O(1()平均)。

10.117.146.16:6379> hset myhash f1 v1
(integer) 1
10.117.146.16:6379> hexists myhash f1
(integer) 1
10.117.146.16:6379> hexists myhash f2
(integer) 0
10.117.146.16:6379> hset myhash f2 v2
(integer) 1
10.117.146.16:6379> hlen myhash
(integer) 2

Redis 的 list 类型其实就是一个每个子元素都是 string 类型的双向链表。链表的最大长度是(2 的 32 次方)。

我们可以通过 push,pop 操作从链表的头部或者尾部添加删除元素。这使得 list 既可以用作栈,也可以用作队列。

当我们[lr]pop 一个 list 对象时,如果 list 是空, 或者不存在,会立即返回 nil。但是阻塞版本的 b[lr]pop 可以则可以阻塞,
当然可以加超时时 间,超时后也会返回 nil。

lrem：从 key 对应 list 中删除 count 个和 value 相同的元素。

10.117.146.16:6379> lrange mylist 0 -1
1) "hello"
2) "here"
3) "world"
10.117.146.16:6379> lrem mylist 1 ‘here‘
(integer) 1
10.117.146.16:6379> lrange mylist 0 -1
1) "hello"
2) "world"