Redis Sets are an unordered collection of unique strings. Unique means sets does not allow repetition of data in a key.

In Redis set add, remove, and test for the existence of members in O(1) (constant time regardless of the number of elements contained inside the Set). The maximum length of a list is 232 – 1 elements (4294967295, more than 4 billion of elements per set).

Example

redis 127.0.0.1:6379> SADD tutorials redis 
(integer) 1 
redis 127.0.0.1:6379> SADD tutorials mongodb 
(integer) 1 
redis 127.0.0.1:6379> SADD tutorials mysql 
(integer) 1 
redis 127.0.0.1:6379> SADD tutorials mysql 
(integer) 0 
redis 127.0.0.1:6379> SMEMBERS tutorials  
1) "mysql" 
2) "mongodb" 
3) "redis"

In the above example, three values are inserted in Redis set named ‘tutorials’ by the command SADD.

Redis Sets Commands

Following table lists some basic commands related to sets.

Sr.NoCommand & Description
1SADD key member1 [member2]Adds one or more members to a set
2SCARD keyGets the number of members in a set
3SDIFF key1 [key2]Subtracts multiple sets
4SDIFFSTORE destination key1 [key2]Subtracts multiple sets and stores the resulting set in a key
5SINTER key1 [key2]Intersects multiple sets
6SINTERSTORE destination key1 [key2]Intersects multiple sets and stores the resulting set in a key
7SISMEMBER key memberDetermines if a given value is a member of a set
8SMEMBERS keyGets all the members in a set
9SMOVE source destination memberMoves a member from one set to another
10SPOP keyRemoves and returns a random member from a set
11SRANDMEMBER key [count]Gets one or multiple random members from a set
12SREM key member1 [member2]Removes one or more members from a set
13SUNION key1 [key2]Adds multiple sets
14SUNIONSTORE destination key1 [key2]Adds multiple sets and stores the resulting set in a key
15SSCAN key cursor [MATCH pattern] [COUNT count]Incrementally iterates set elements

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