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Redis Sorted Sets are similar to Redis Sets with the unique feature of values stored in a set. The difference is, every member of a Sorted Set is associated with a score, that is used in order to take the sorted set ordered, from the smallest to the greatest score.
In Redis sorted 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). 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> ZADD tutorials 1 redis (integer) 1 redis 127.0.0.1:6379> ZADD tutorials 2 mongodb (integer) 1 redis 127.0.0.1:6379> ZADD tutorials 3 mysql (integer) 1 redis 127.0.0.1:6379> ZADD tutorials 3 mysql (integer) 0 redis 127.0.0.1:6379> ZADD tutorials 4 mysql (integer) 0 redis 127.0.0.1:6379> ZRANGE tutorials 0 10 WITHSCORES 1) "redis" 2) "1" 3) "mongodb" 4) "2" 5) "mysql" 6) "4"
In the above example, three values are inserted with its score in Redis sorted set named ‘tutorials’ by the command ZADD.
Redis Sorted Sets Commands
Following table lists some basic commands related to sorted sets.
| Sr.No | Command & Description |
|---|---|
| 1 | ZADD key score1 member1 [score2 member2]
Adds one or more members to a sorted set, or updates its score, if it already exists |
| 2 | ZCARD key
Gets the number of members in a sorted set |
| 3 | ZCOUNT key min max
Counts the members in a sorted set with scores within the given values |
| 4 | ZINCRBY key increment member Increments the score of a member in a sorted set |
| 5 | ZINTERSTORE destination numkeys key [key …]
Intersects multiple sorted sets and stores the resulting sorted set in a new key |
| 6 | ZLEXCOUNT key min max
Counts the number of members in a sorted set between a given lexicographical range |
| 7 | ZRANGE key start stop [WITHSCORES]
Returns a range of members in a sorted set, by index |
| 8 | ZRANGEBYLEX key min max [LIMIT offset count]
Returns a range of members in a sorted set, by lexicographical range |
| 9 | ZRANGEBYSCORE key min max [WITHSCORES] [LIMIT]
Returns a range of members in a sorted set, by score |
| 10 | ZRANK key member
Determines the index of a member in a sorted set |
| 11 | ZREM key member [member …]
Removes one or more members from a sorted set |
| 12 | ZREMRANGEBYLEX key min max
Removes all members in a sorted set between the given lexicographical range |
| 13 | ZREMRANGEBYRANK key start stop
Removes all members in a sorted set within the given indexes |
| 14 | ZREMRANGEBYSCORE key min max
Removes all members in a sorted set within the given scores |
| 15 | ZREVRANGE key start stop [WITHSCORES]
Returns a range of members in a sorted set, by index, with scores ordered from high to low |
| 16 | ZREVRANGEBYSCORE key max min [WITHSCORES]
Returns a range of members in a sorted set, by score, with scores ordered from high to low |
| 17 | ZREVRANK key member
Determines the index of a member in a sorted set, with scores ordered from high to low |
| 18 | ZSCORE key member
Gets the score associated with the given member in a sorted set |
| 19 | ZUNIONSTORE destination numkeys key [key …]
Adds multiple sorted sets and stores the resulting sorted set in a new key |
| 20 | ZSCAN key cursor [MATCH pattern] [COUNT count]
Incrementally iterates sorted sets elements and associated scores |
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