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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.No | Command & Description |
|---|---|
| 1 | SADD key member1 [member2]
Adds one or more members to a set |
| 2 | SCARD key
Gets the number of members in a set |
| 3 | SDIFF key1 [key2]
Subtracts multiple sets |
| 4 | SDIFFSTORE destination key1 [key2]
Subtracts multiple sets and stores the resulting set in a key |
| 5 | SINTER key1 [key2]
Intersects multiple sets |
| 6 | SINTERSTORE destination key1 [key2]
Intersects multiple sets and stores the resulting set in a key |
| 7 | SISMEMBER key member
Determines if a given value is a member of a set |
| 8 | SMEMBERS key
Gets all the members in a set |
| 9 | SMOVE source destination member
Moves a member from one set to another |
| 10 | SPOP key
Removes and returns a random member from a set |
| 11 | SRANDMEMBER key [count]
Gets one or multiple random members from a set |
| 12 | SREM key member1 [member2]
Removes one or more members from a set |
| 13 | SUNION key1 [key2]
Adds multiple sets |
| 14 | SUNIONSTORE destination key1 [key2]
Adds multiple sets and stores the resulting set in a key |
| 15 | SSCAN key cursor [MATCH pattern] [COUNT count]
Incrementally iterates set elements |
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