Redis Set
Redis’ Set is an unordered collection of string type. Set members are unique, which means that duplicate data cannot appear in the set.
In Redis, collections are implemented through hash tables, so the complexity of adding, deleting, and searching is O(1).
The maximum number of members in a collection is 232 - 1 (4294967295, each collection can store more than 4 billion members).
Example
redis 127.0.0.1:6379> SADD w3ckey redis (integer) 1 redis 127.0.0.1:6379> SADD w3ckey mongodb (integer) 1 redis 127.0.0.1:6379> SADD w3ckey mysql (integer) 1 redis 127.0.0.1:6379> SADD w3ckey mysql (integer) 0 redis 127.0.0.1:6379> SMEMBERS w3ckey 1) "mysql" 2) "mongodb" 3) "redis"
In the above example, we inserted three elements into the collection named w3ckey through the SADD command.
Redis collection commands
The following table lists the basic commands of Redis collection:
| Serial number | Command and description |
|---|---|
| 1 | SADD key member1 [member2] Add one or more members to the collection |
| 2 | SCARD key Get the number of members of the set |
| 3 | SDIFF key1 [key2] Return all given sets The difference set |
| 4 | SDIFFSTORE destination key1 [key2] Returns the difference set of all given sets and stores it in destination |
| 5 | SINTER key1 [key2] Returns the intersection of all given sets |
| 6 | SINTERSTORE destination key1 [key2] Return the intersection of all given sets and store it in destination |
| 7 | SISMEMBER key member Determine whether the member element is a set key Members of |
| 8 | SMEMBERS key Returns all members in the set |
| 9 | SMOVE source destination member Move the member element from the source collection to the destination collection |
| 10 | SPOP key Remove and return one of the collections Random element |
| 11 | SRANDMEMBER key [count] Returns one or more random numbers in the set |
| 12 | SREM key member1 [member2] Remove one or more members in the set |
| 13 | SUNION key1 [key2] Return the union of all given sets |
| 14 | SUNIONSTORE destination key1 [key2] The union of all given sets is stored in the destination set |
| 15 | SSCAN key cursor [MATCH pattern] [COUNT count] Iterate over the elements in the collection |
