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ZRANK

Returns the rank of a member in a sorted set, with the scores ordered from low to high. The rank is 0-based, meaning that the member with the lowest score has rank 0.

Syntax​

ZRANK key member

Parameters​

  • key: The name of the sorted set.
  • member: The member whose rank you want to determine.

Details​

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

The ZRANK command returns the rank of a specified member in the sorted set stored at key, with scores ordered from low to high. If the member exists in the sorted set, the command returns its rank as an integer. If the member does not exist, ZRANK returns nil.

Examples​

Basic Usage​

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

ZADD myzset 1 "a" 2 "b" 3 "c" 4 "d" 5 "e"

To get the rank of member "c":

ZRANK myzset "c"

This will return:

(integer) 2

Member Not Found​

If you try to get the rank of a member that does not exist in the sorted set:

ZRANK myzset "f"

This will return:

(nil)

Edge Cases​

  • If the member does not exist in the sorted set, ZRANK returns nil.
  • If the key does not exist, ZRANK returns nil.
  • If the key exists but is not a sorted set, an error is returned.

RESP2/RESP3 Reply​

  • Integer reply: the rank of the member if it exists, or nil if the member does not exist.