Redis无序集合数据类型操作命令
Set是集合，它是string类型的无序集合。set是通过hash table实现的，添加删除和查找的负责度都是0（1）。对集合我们可以取并集，交集、差集。通过这些操作我们可以实现QQ和微博中的好友推荐和blog的tag功能。sadd：向名称为key的set中添加元素
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127.0.0.1:6379> sadd myset1 one
(integer) 1
127.0.0.1:6379> sadd myset1 two
(integer) 1
127.0.0.1:6379> sadd myset1 two
(integer) 0
smembers: 查看集合中的所有元素
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127.0.0.1:6379> smembers myset1
1) "two"
2) "one"
srem：删除集合中的元素
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127.0.0.1:6379> sadd myset2 "one"
(integer) 1
127.0.0.1:6379> sadd myset2 "two"
(integer) 1
127.0.0.1:6379> srem myset2 "one"
(integer) 1
127.0.0.1:6379> smembers myset2
1) "two"
spop：随机返回并删除名称为key的set中的一个元素
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127.0.0.1:6379> smembers myset2
1) "two"
2) "three"
3) "one"
127.0.0.1:6379> spop myset2
"two"
127.0.0.1:6379> smembers myset2
1) "three"
2) "one"
sdiff：返回所有给定key与第一个key的差集
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127.0.0.1:6379> smembers myset3
1) "two"
2) "four"
3) "three"
4) "one"
127.0.0.1:6379> smembers myset2
1) "three"
2) "one"
127.0.0.1:6379> sdiff myset3 myset2
1) "two"
2) "four"
127.0.0.1:6379> sdiff myset2 myset3
(empty list or set)
注意sdiff myset2 myset3 与 sdiff myset3 myset2的区别
sdiffstore：返回所有给定key与第一个key的差集，并将结果存为另一个key
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127.0.0.1:6379> sdiff myset3 myset2
1) "two"
2) "four"
127.0.0.1:6379> sdiffstore myset4 myset3 myset2
(integer) 2
127.0.0.1:6379> smembers myset4
1) "two"
2) "four"
sinter：返回所有给定key的交集
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127.0.0.1:6379> smembers myset2
1) "three"
2) "one"
127.0.0.1:6379> smembers myset3
1) "two"
2) "four"
3) "three"
4) "one"
127.0.0.1:6379> sinter myset2 myset3
1) "three"
2) "one"
sinterstore：返回所有给定key的交集，并将结果存为另一个key
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127.0.0.1:6379> smembers myset3
1) "two"
2) "four"
3) "three"
4) "one"
127.0.0.1:6379> sinter myset2 myset3
1) "three"
2) "one"
127.0.0.1:6379> sinterstore myset5 myset2 myset3
(integer) 2
127.0.0.1:6379> smembers myset5
1) "three"
2) "one"
sunion：返回所有给定key的并集
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127.0.0.1:6379> smembers myset2
1) "three"
2) "one"
127.0.0.1:6379> smembers myset3
1) "two"
2) "four"
3) "three"
4) "one"
127.0.0.1:6379> sunion myset2 myset3
1) "four"
2) "three"
3) "one"
4) "two"
suionstore：返回所有给定key的并集，并将结果存为另一个key
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127.0.0.1:6379> smembers myset2
1) "three"
2) "one"
127.0.0.1:6379> smembers myset3
1) "two"
2) "four"
3) "three"
4) "one"
127.0.0.1:6379> sunionstore myset6 myset2 myset3
(integer) 4
127.0.0.1:6379> smembers myset6
1) "four"
2) "three"
3) "one"
4) "two"
smove：从第一个key对应的set中移除member并添加到第二个对应的set中
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127.0.0.1:6379> smembers myset3
1) "two"
2) "four"
3) "three"
4) "one"
127.0.0.1:6379> smembers myset2
1) "three"
2) "one"
127.0.0.1:6379> smove myset3 myset2 two
(integer) 1
127.0.0.1:6379> smembers myset2
1) "two"
2) "three"
3) "one"
127.0.0.1:6379> smembers myset3
1) "four"
2) "three"
3) "one"
scard：返回名称为key的集合的元素个数
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127.0.0.1:6379> smembers myset3
1) "four"
2) "three"
3) "one"
127.0.0.1:6379> scard myset3
(integer) 3
sismember：测试member是否是名称为key的set的元素，如果是则返回1，否则返回0
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127.0.0.1:6379> smembers myset3
1) "four"
2) "three"
3) "one"
127.0.0.1:6379> sismember myset3 one
(integer) 1
127.0.0.1:6379> sismember myset3 two
(integer) 0
srandmember：随机返回名称为key的set的一个元素，但不删除元素
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srandmember key
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127.0.0.1:6379> smembers myset3
1) "four"
2) "three"
3) "one"
127.0.0.1:6379> srandmember myset3
"one"
127.0.0.1:6379> srandmember myset3
"four"
127.0.0.1:6379> srandmember myset3
"three"
127.0.0.1:6379> srandmember myset3
"one"
127.0.0.1:6379> srandmember myset3
"three"
还可以传递count参数来一次随机获得多个元素。根据count值不同，意义也不相同
1、count为正数时，会随机从集合中获得count个不重复元素，如果count值大于集合元素的个数，则返回集合中所有元素
2、count为负数时，srandmember会随机从集合中返回|count|个元素，这些元素可能会重复
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127.0.0.1:6379> smembers myset3
1) "four"
2) "three"
3) "one"
127.0.0.1:6379> srandmember myset3 5
1) "three"
2) "four"
3) "one"
127.0.0.1:6379> srandmember myset3 2
1) "four"
2) "one"
127.0.0.1:6379> srandmember myset3 -2
1) "four"
2) "one"
127.0.0.1:6379> srandmember myset3 -2
1) "one"
2) "four"
127.0.0.1:6379> srandmember myset3 -2
1) "one"
2) "one"
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