ZRANK

Syntax

ZRANK key member [WITHSCORE]

Parameters

Parameter	Description	Type	Required
key	The key of the sorted set.	String	Yes
member	The member whose rank is to be determined.	String	Yes
WITHSCORE	If provided, the command will also return the score of the member.	String	No

Return values

Condition	Return Value
If member exists in the sorted set	Integer (rank of the member)
If WITHSCORE option is used	Array (rank and score of the member)
If member or key does not exist	nil

Behaviour

• The ZRANK command searches for the specified member within the sorted set associated with the given key.
• If the key exists and is a sorted set, the command returns the rank of the member based on its score, with the lowest score having rank 0.
• If the WITHSCORE option is provided, the command returns both the rank and the score of the member as an array.
• If the key does not exist or the member is not found in the sorted set, the command returns nil.

Errors

1. Wrong type of value or key:

   • Error Message: (error) WRONGTYPE Operation against a key holding the wrong kind of value
   • Occurs when the specified key exists but is not associated with a sorted set.

2. Invalid syntax or number of arguments:

   • Error Message: (error) ERR wrong number of arguments for 'zrank' command
   • Occurs if the command is issued with an incorrect number of arguments.

3. Invalid option:

   • Error Message: (error) ERR syntax error
   • Occurs if an invalid option is provided.

Example Usage

Basic Usage

Retrieve the rank of member1 in the sorted set myzset:

127.0.0.1:7379> ZADD myzset 1 member1 2 member2 3 member3
(integer) 3
127.0.0.1:7379> ZRANK myzset member1
(integer) 0
127.0.0.1:7379> ZRANK myzset member3
(integer) 2

Using WITHSCORE Option

Retrieve both the rank and the score of member2 in the sorted set myzset:

127.0.0.1:7379> ZADD myzset 1 member1 2 member2
(integer) 2
127.0.0.1:7379> ZRANK myzset member2 WITHSCORE
(integer) [1, 2]

Best Practices

• Use ZRANK in combination with ZADD and ZSCORE for efficient management of sorted sets and leaderboards.

Notes

• This command is particularly useful for implementing leaderboards, pagination in ranked lists, and analytics on data distribution.