 Usage:

ZRANDMEMBER key [ count [ withscores ] ]
 Complexity:
 O(N) where N is the number of members returned
 Since:
 6.2.0
 No repeated elements are returned.
 If
count
is bigger than the cardinality of the sorted set, the command will only return the whole sorted set without additional elements.  The order of elements in the reply is not truly random, so it is up to the client to shuffle them if needed.
 Repeating elements are possible.
 Exactly
count
elements, or an empty array if the sorted set is empty (nonexisting key), are always returned.  The order of elements in the reply is truly random.
When called with just the key
argument, return a random element from the sorted set value stored at key
.
If the provided count
argument is positive, return an array of distinct elements.
The array's length is either count
or the sorted set's cardinality (ZCARD
), whichever is lower.
If called with a negative count
, the behavior changes and the command is allowed to return the same element multiple times.
In this case, the number of returned elements is the absolute value of the specified count
.
The optional WITHSCORES
modifier changes the reply so it includes the respective scores of the randomly selected elements from the sorted set.
Examples
127.0.0.1:6379> ZADD dadi 1 uno 2 due 3 tre 4 quattro 5 cinque 6 sei
(integer) 6
127.0.0.1:6379> ZRANDMEMBER dadi
"uno"
127.0.0.1:6379> ZRANDMEMBER dadi
"uno"
127.0.0.1:6379> ZRANDMEMBER dadi 5 WITHSCORES
1) "cinque"
2) "5"
3) "sei"
4) "6"
5) "quattro"
6) "4"
7) "quattro"
8) "4"
9) "sei"
10) "6"
Specification of the behavior when count is passed
When the count
argument is a positive value this command behaves as follows:
When the count
is a negative value, the behavior changes as follows: