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SRANDMEMBER

Syntax​

SRANDMEMBER key [count]

Time complexity: Without the count argument O(1), otherwise O(N) where N is the absolute value of the passed count.

ACL categories: @read, @set, @slow

When called with just the key argument, return a random element from the 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 set's cardinality (SCARD), 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.

Return​

When called without the count argument:

Bulk string reply: the random member, or nil when key does not exist.

When called with the count argument:

Array reply: the random members, or an empty array when key does not exist.

Examples​

dragonfly> SADD myset one two three
(integer) 3
dragonfly> SRANDMEMBER myset
"three"
dragonfly> SRANDMEMBER myset 2
1) "one"
2) "three"
dragonfly> SRANDMEMBER myset -5
1) "two"
2) "one"
3) "one"
4) "one"
5) "two"

Distribution of returned elements​

Note that this command is not suitable when you need a guaranteed uniform distribution of the returned elements.