Redis Sorted Set

Redis sorted sets, like sets, are collections of string-type elements, and duplicate members are not allowed.

The difference is that each element is associated with a double-type score. Redis uses the score to sort the members in the set from smallest to largest.

The members of a sorted set are unique, but scores can be repeated.

Sets are implemented through hash tables, so the complexity of adding, deleting, and searching is O(1). The maximum number of members in a set is 2³²- 1 (4294967295, each set can store more than 4 billion members).

Example

redis 127.0.0.1:6379> ZADD examplekey 1 redis
(integer) 1
redis 127.0.0.1:6379> ZADD examplekey 2 mongodb
(integer) 1
redis 127.0.0.1:6379> ZADD examplekey 3 mysql
(integer) 1
redis 127.0.0.1:6379> ZADD examplekey 3 mysql
(integer) 0
redis 127.0.0.1:6379> ZADD examplekey 4 mysql
(integer) 0
redis 127.0.0.1:6379> ZRANGE examplekey 0 10 WITHSCORES

1) "redis"
2) "1"
3) "mongodb"
4) "2"
5) "mysql"
6) "4"

In the above example, we used the commandZADDto add three values to the Redis sorted set and associate them with scores.

Redis Sorted Set Commands

The following table lists the basic commands of Redis sorted sets: