- Usage:
-
SPOP key [ count ]
- Complexity:
- Without the count argument O(1), otherwise O(N) where N is the value of the passed count.
- Since:
- 1.0.0
Removes and returns one or more random members from the set value store at key.
This operation is similar to SRANDMEMBER, that returns one or more random elements from a set but does not remove it.
By default, the command pops a single member from the set. When provided with
the optional count argument, the reply will consist of up to count members,
depending on the set's cardinality.
Examples
127.0.0.1:6379> SADD myset "one"
(integer) 1
127.0.0.1:6379> SADD myset "two"
(integer) 1
127.0.0.1:6379> SADD myset "three"
(integer) 1
127.0.0.1:6379> SPOP myset
"three"
127.0.0.1:6379> SMEMBERS myset
1) "one"
2) "two"
127.0.0.1:6379> SADD myset "four"
(integer) 1
127.0.0.1:6379> SADD myset "five"
(integer) 1
127.0.0.1:6379> SPOP myset 3
1) "one"
2) "four"
3) "five"
127.0.0.1:6379> SMEMBERS myset
1) "two"
Distribution of returned elements
Note that this command is not suitable when you need a guaranteed uniform distribution of the returned elements. For more information about the algorithms used for SPOP, look up both the Knuth sampling and Floyd sampling algorithms.
History
| Version | Change |
|---|---|
| 3.2.0 | Added the |