Skip to main content

ZPOPMAX

Removes and returns one or more members with the highest scores in a sorted set.

Syntax​

ZPOPMAX key [count]

Parameters​

  • key: The name of the sorted set.
  • count: Optional. Specifies the number of members to pop. If not provided, the default is 1.

Details​

  • Available since: 5.0.0
  • Time complexity: O(log(N) * M) with N being the number of elements in the sorted set and M being the number of elements popped.
  • ACL categories: @write, @sortedset, @fast

The ZPOPMAX command is used to remove and return the member(s) with the highest score(s) from the sorted set stored at key. If multiple members have the same highest score, they are returned in lexicographical order.

Examples​

Basic Usage​

Assume we have a sorted set called myzset with the following members:

ZADD myzset 1 "a" 2 "b" 3 "c"

To pop the member with the highest score:

ZPOPMAX myzset

This will return:

1) "c"
2) "3"

Popping Multiple Members​

To pop the two members with the highest scores:

ZPOPMAX myzset 2

This will return:

1) "c"
2) "3"
3) "b"
4) "2"

Handling an Empty Set​

If myzset is now empty and we try to pop again:

ZPOPMAX myzset

This will return:

(nil)

Edge Cases​

  • If the sorted set is empty, ZPOPMAX returns a nil reply.
  • If the specified count is greater than the number of available members, all members are returned.
  • If the key does not exist, ZPOPMAX returns a nil reply.
  • If the key exists but is not a sorted set, an error is returned.

RESP2/RESP3 Reply​

  • Array reply: list of members and their scores, ordered from the highest to the lowest scores.