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ZCOUNT

Returns the number of elements in the sorted set at the specified key with a score between the given minimum and maximum values.

Syntax​

ZCOUNT key min max

Parameters​

  • key: The name of the sorted set.
  • min: The minimum score (inclusive) of the range.
  • max: The maximum score (inclusive) of the range.

Details​

  • Available since: 2.0.0
  • Time complexity: O(log(N)) with N being the number of elements in the sorted set.
  • ACL categories: @read, @sortedset, @fast

The min and max parameters can be specified with the following options:

  • Include the value with the score by using the score directly (e.g., 2).
  • Exclude the value with the score by prefixing the score with an open parenthesis (e.g., (2).
  • Use -inf and +inf to represent the minimum and maximum possible scores, respectively.

Examples​

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

ZADD myzset 1 "member1" 2 "member2" 3 "member3" 4 "member4"

To count the number of members with scores between 2 and 3 inclusive:

ZCOUNT myzset 2 3

This will return:

(integer) 2

To count the number of members with scores greater than 2 but less than or equal to 4:

ZCOUNT myzset (2 4

This will return:

(integer) 2

Edge Cases​

  • If min is greater than max, ZCOUNT returns 0.
  • If the sorted set does not exist, ZCOUNT returns 0.
  • If the key exists but is not a sorted set, an error is returned.

RESP2/RESP3 Reply​

  • Integer reply: the number of elements in the specified score range.