Redis series - Storage articles hash major operating functions Summary
hash is a series key value (field value) mapping table. Some examples of storage objects often use it. With respect to the various fields of an object is stored string, it is stored as a hash takes up less memory. Why would save more memory? Need to figure out the meaning of two configuration (hash-max-zipmap-entries and hash-max-zipmap-value), detailing the configuration, I intend to put the final configuration to optimize link speak.
1) New
a）hset
语法：hset key field value解释：设置hash表key中的field的值。如果hash表不存在，则创建，并执行设置field的值，如果hash表存在，值field的值覆盖或新增[root@localhost ~]# redis-cli
redis 127.0.0.1:6379> hset user.1 name lisi #设置key user.1 name域 的值
(integer) 1
redis 127.0.0.1:6379> hset user.1 age 45 #设置age域
(integer) 1
redis 127.0.0.1:6379> hset user.1 tech lisi
(integer) 1b）hmset
语法：hash key field value[key value]
解释：批量设置hash表key的域
redis 127.0.0.1:6379> hmset user.2 name niuer age 34 #同时设置name 和age域
OKc）hsetnx
语法：hsetnx key field value
解释：仅仅当field域不存在时，设置hash表field的值
redis 127.0.0.1:6379> hsetnx user.1 name lisi #由于name域已经设置过，所以返回0
(integer) 0
redis 127.0.0.1:6379> hsetnx user.1 fri 5
(integer) 1 #fri域没有设置过，所以hset并返回12) query
a）hget
语法：hget key field
解释：获取哈希表key的field值
redis 127.0.0.1:6379> hget user.1 name #存在的hash表及域
"lisi"
redis 127.0.0.1:6379> hget user.3 name #不存在的hash表
(nil)
redis 127.0.0.1:6379> hget user.1 bb #不存在的域
(nil)b）hmget
语法：hmget key field[field]
解释：批量获取hash表的filed
redis 127.0.0.1:6379> hmget user.1 name age fri tech
1) "lisi"
2) "45"
3) "5"
4) "lisi"
redis 127.0.0.1:6379> hmget user.1 name age fri tech nofield #存在hash表中包含不存在的域nofield
1) "lisi"
2) "45"
3) "5"
4) "lisi"
5) (nil)
redis 127.0.0.1:6379> hmget user.3 name age fri #不存在的hash表
1) (nil)
2) (nil)
3) (nil)c）hgetall
语法：hgetall key
解释：获取hash表的所有域值
redis 127.0.0.1:6379> hgetall user.2 #存在的hash表
1) "name" #域
2) "niuer" #域name的值
3) "age" #域
4) "34" #域age的值
redis 127.0.0.1:6379> hgetall user.3 #不存在的hansh表
(empty list or set)d）hexists
语法：hexists key field
解释：判断hash表中是否存在某个域
redis 127.0.0.1:6379> hexists user.1 name #存在
(integer) 1
redis 127.0.0.1:6379> hexists user.1 nofield #不存在
(integer) 0
redis 127.0.0.1:6379> hexists use1 nofield #hash表不存在
(integer) 0e) hkeys
语法：hkeys key
解释：获取hash表的所有域
redis 127.0.0.1:6379> hkeys user.1 #存在的hash表
1) "name"
2) "age"
3) "tech"
4) "fri"
redis 127.0.0.1:6379> hkeys user.4 #不存在的hash
(empty list or set)f) whale
语法：hvals key
解释：获取hash表的所有域值
redis 127.0.0.1:6379> hvals user.1 #存在hash
1) "lisi"
2) "45"
3) "lisi"
4) "5"
redis 127.0.0.1:6379> hvals user.4 #不存在
(empty list or set)3) Modify
语法：hincrby key field increment
解释：hash表field域的数值增加步长increment，如果increment是负值，则是递减。如果域不存在，初始值视为0
redis 127.0.0.1:6379> hincrby user.1 age 2 #增加2
(integer) 47
redis 127.0.0.1:6379> hincrby user.1 age -3 #减少3
(integer) 44
redis 127.0.0.1:6379> hincrby user.1 age2 -3 #域不能存在，初始值是0
(integer) -34) Delete
语法：hdel key field[field]
解释：删除hash的域，如果指定多个field，则删除多个
redis 127.0.0.1:6379> hkeys user.1
1) "name"
2) "age"
3) "tech"
4) "fri"
5) "age2"
redis 127.0.0.1:6379> hdel user.1 age2 #删除一个域
(integer) 1
redis 127.0.0.1:6379> hkeys user.1
1) "name"
2) "age"
3) "tech"
4) "fri"
redis 127.0.0.1:6379> hdel user.1 fri tech #删除2个域
(integer) 2
redis 127.0.0.1:6379> hkeys user.1
1) "name"
2) "age"
redis 127.0.0.1:6379> hdel user.1 bb #删除一个不存在的域
(integer) 0 #返回05) Other
语法：hlen key
解释：获取hash的域数量
redis 127.0.0.1:6379> hkeys user.1
1) "name"
2) "age"
redis 127.0.0.1:6379> hlen user.1 #存在2个域
(integer) 2
redis 127.0.0.1:6379> hlen user.4 #不存在的hash
(integer) 0For more detailed usage hash, see: http: //redis.io/commands#hash