What is the TairZset extended data structure - Tair (Redis® OSS-Compatible)

TairZset (exZset) enables you to sort items by scores with up to 256 dimensions of the double type. This feature is useful for leaderboards in industries such as gaming, live streaming, music, and e-commerce. It greatly improves data processing efficiency and simplifies client-side implementation because it does not require encoding or decoding.

Introduction to TairZset

The native Redis Sorted Set (also known as Zset) supports sorting by only a single double-precision score. This makes it difficult to implement multi-dimensional sorting. For example, using methods such as IEEE 754 bit-level concatenation is complex, reduces precision, and prevents the use of the EXZINCRBY command.

The TairZset data structure, developed by Alibaba Cloud, simplifies the implementation of multi-dimensional sorting. It has the following advantages over traditional methods:

Supports sorting by scores with up to 256 dimensions of the double type. The sorting priority is from left to right.
For a multi-dimensional score, the leftmost score has the highest priority. For example, with a three-dimensional score such as score1#score2#score3, TairZset first compares score1. If the score1 values are equal, TairZset then compares score2. If the score2 values are also equal, TairZset compares score3. If all score dimensions are identical, the elements are sorted by lexicographic order (ASCII order).
To make this easier to understand, you can think of the hash symbol (#) as a decimal point (.). For example, the relationship between 0#99, 99#90, and 99#99 can be understood as 0.99 < 99.90 < 99.99. Therefore, 0#99 < 99#90 < 99#99.
Supports the EXZINCRBY command. You no longer need to retrieve the current data, increment the value locally, and then write it back to Tair.
Provides an API similar to the native Zset API.
Provides capabilities for both standard leaderboards and distributed architecture leaderboards .
Provides an open-source TairJedis client. You do not need to perform any encoding or decoding. You can also use the open-source implementation as a reference to develop clients in other languages.

Typical scenarios

TairZset is suitable for leaderboard scenarios in industries such as gaming, live streaming, music, and e-commerce. Examples include the following:

Live streaming leaderboards: In a streamer competition, streamers are first ranked by their current popularity score. If their popularity scores are the same, they are ranked by the number of likes. If the number of likes is also the same, they are ranked by the total value of gifts received.
Medal tables: Participants are ranked based on the number of gold, silver, and bronze medals. They are first sorted by the number of gold medals. If the number of gold medals is the same, they are sorted by the number of silver medals. If the number of silver medals is also the same, they are sorted by the number of bronze medals.
Game leaderboards: Players are ranked based on multiple dimensions, such as score, task completion time, and rank level.

This module is open-source. For more information, see TairZset.

Best practices

Prerequisites

The instance must be a Tair memory-optimized instance. If the instance is a memory-optimized instance compatible with Redis 5.0, its minor version must be 1.7.1 or later.

Note

The latest minor version provides more features and higher stability. We recommend that you update the instance to the latest minor version. For more information, see Update the minor version of an instance. If your instance is a cluster instance or read/write splitting instance, we recommend that you update the proxy nodes in the instance to the latest minor version to ensure that all commands can be run as expected.

Notes

The commands in this topic apply to TairZset data in a Tair instance.

Commands

Command	Syntax	Description
EXZADD	`EXZADD key [NX\|XX] [CH] [INCR] score member [score member ...]`	Stores one or more members with their scores in the TairZset at the specified key. Note To implement multi-dimensional sorting, use a hash symbol (#) to separate the scores for each dimension, such as `111#222#121`. All members in the key must have the same score format.
EXZINCRBY	`EXZINCRBY key increment member`	Increments the score of a member in the TairZset at the specified key by the value of increment.
EXZSCORE	`EXZSCORE key member`	Returns the score of a member in the TairZset at the specified key. If the key or member does not exist, it returns nil.
EXZRANGE	`EXZRANGE key min max [WITHSCORES]`	Returns the specified range of elements from the TairZset at the specified key.
EXZREVRANGE	`EXZREVRANGE key min max [WITHSCORES]`	Returns the specified range of elements from the TairZset at the specified key. Elements are ordered from high to low score. Elements with the same score are ordered in reverse lexicographic order. Note Other than the reverse sorting order, this command is similar to EXZRANGE.
EXZRANGEBYSCORE	`EXZRANGEBYSCORE key min max [WITHSCORES] [LIMIT offset count]`	Returns all elements in the TairZset at the specified key with a score between min and max (inclusive). Elements are ordered from low to high score. Elements with the same score are ordered by lexicographic order.
EXZREVRANGEBYSCORE	`EXZREVRANGEBYSCORE key max min [WITHSCORES] [LIMIT offset count]`	Returns all elements in the TairZset at the specified key with a score between min and max (inclusive). Unlike the default sorting order, this command returns elements ordered from high to low score. Elements with the same score are ordered in reverse lexicographic order. Note Other than the reverse sorting order, this command is similar to EXZRANGEBYSCORE. Note that max comes before min in this command.
EXZRANGEBYLEX	`EXZRANGEBYLEX key min max [LIMIT offset count]`	When all elements in a TairZset have the same score, this command returns all elements at the specified key that are between the min and max lexicographical range.
EXZREVRANGEBYLEX	`EXZREVRANGEBYLEX key max min [LIMIT offset count]`	When all elements in a TairZset have the same score, this command returns all elements at the specified key that are between the max and min lexicographical range. Note Other than the reverse sorting order, this command is similar to EXZRANGEBYLEX. Note that max comes before min in this command.
EXZREM	`EXZREM key member [member ...]`	Removes the specified members from the TairZset at the specified key. Non-existent members are ignored.
EXZREMRANGEBYSCORE	`EXZREMRANGEBYSCORE key min max`	Removes all elements in the TairZset at the specified key with a score between min and max (inclusive).
EXZREMRANGEBYRANK	`EXZREMRANGEBYRANK key start stop`	Removes all elements in the TairZset at the specified key with a rank between start and stop.
EXZREMRANGEBYLEX	`EXZREMRANGEBYLEX key min max`	When all elements in a TairZset have the same score, this command removes all elements at the specified key that are between the max and min lexicographical range. Note If you run this command and the EXZRANGEBYLEX command with the same min and max parameter values, this command removes the same elements that the EXZRANGEBYLEX command returns.
EXZCARD	`EXZCARD key`	Returns the cardinality (number of elements) of the TairZset at the specified key.
EXZRANK	`EXZRANK key member`	Returns the rank of a member in the TairZset at the specified key, with scores ordered from low to high. The rank (or index) is 0-based, so the member with the lowest score has a rank of 0.
EXZREVRANK	`EXZREVRANK key member`	Returns the rank of a member in the TairZset at the specified key, with scores ordered from high to low. The rank (or index) is 0-based, so the member with the highest score has a rank of 0. Note Other than the reverse sorting order, this command is similar to EXZRANK.
EXZCOUNT	`EXZCOUNT key min max`	Returns the number of elements in the TairZset at the specified key with a score between min and max.
EXZLEXCOUNT	`EXZLEXCOUNT key min max`	When all elements in a TairZset have the same score, this command returns the number of elements at the specified key that are between the min and max lexicographical range.
EXZRANKBYSCORE	`EXZRANKBYSCORE key score`	Calculates the rank of a given score in the TairZset at the specified key, with scores ordered from low to high. The rank (or index) is 0-based, so the member with the lowest score has a rank of 0. Note If the specified score does not exist, the command returns the prospective rank of that score in the TairZset. If the specified score already exists, Tair ranks the specified score before the existing score by default.
EXZREVRANKBYSCORE	`EXZREVRANKBYSCORE key score`	Calculates the rank of a given score in the TairZset at the specified key, with scores ordered from high to low. The rank (or index) is 0-based, so the member with the highest score has a rank of 0. Note If the specified score does not exist, the command returns the prospective rank of that score in the TairZset. If the specified score already exists, Tair ranks the specified score after the existing score by default.
DEL	`DEL key [key ...]`	Deletes one or more TairZset keys using the native Redis DEL command.

Note

The following list describes the conventions for the command syntax used in this topic:

Uppercase keyword: indicates the command keyword.
Italic text: indicates variables.
[options]: indicates that the enclosed parameters are optional. Parameters that are not enclosed by brackets must be specified.
A|B: indicates that the parameters separated by the vertical bars (|) are mutually exclusive. Only one of the parameters can be specified.
...: indicates that the parameter preceding this symbol can be repeatedly specified.

EXZADD

Category	Description
Syntax	`EXZADD key [NX\|XX] [CH] [INCR] score member [score member ...]`
Time complexity	O(N)
Command description	Stores one or more members with their scores in the TairZset at the specified key. The system performs different actions based on whether the key and member exist: If the specified key or member does not exist, the system creates it and inserts the score. If the specified key and member already exist, the system updates (overwrites) the score. Each score is represented as a string of a double-precision floating-point number. +inf and -inf are valid values. Note To implement multi-dimensional sorting, use a hash symbol (#) to separate the scores for each dimension, such as `111#222#121`. All members in the key must have the same score format.
Options	NX: Adds only new elements. Does not update existing elements. XX: Updates only existing elements. Does not add new elements. CH: Normally, this command returns the number of new elements added. This option changes the return value to the total number of elements that changed. Note Changed elements include new elements and existing elements whose scores were updated. Therefore, if the score of an existing element in the command does not change, it is not counted as a changed element. INCR: When this option is specified, EXZADD behaves like EXZINCRBY. In this mode, you can specify only one score-element pair.
Return value	An integer that indicates the following: If no options are specified, returns the number of elements added to the key (excluding elements whose scores were only updated). If the CH option is specified, returns the number of elements that were changed (added or updated). If the INCR option is specified, returns the new score of the member as a string. If you use multi-dimensional scores, the format is `"score1#score2#score3#..."`, such as `2#0#6`. Note If the operation is aborted (because the command includes the XX or NX option), it returns nil.
Examples	Command example: `EXZADD testkey NX 1#0#3 a 1#0#2 b` Return example: `(integer) 2`

EXZINCRBY

Category	Description
Syntax	`EXZINCRBY key increment member`
Time complexity	O(log(N))
Command description	Increments the score of a member in the TairZset at the specified key by the value of increment. The system performs different actions based on whether the key and member exist: If the specified key or member does not exist, the system creates it and inserts the score. If the specified key and member already exist, the system updates (increments) the score. Each score is represented as a string of a double-precision floating-point number. +inf and -inf are valid values. Note To implement multi-dimensional sorting, use a hash symbol (#) to separate the scores for each dimension, such as `111#222#121`. All members in the key must have the same score format. The score value must be a string representation of a numeric value, which can be a double-precision floating-point number. To decrease the score of a member, specify a negative number.
Options	None
Return value	Returns the new score of the member as a string. If you use multi-dimensional scores, the format is `"score1#score2#score3#..."`, such as `2#0#6`.
Examples	Command example: `EXZINCRBY testkey 2#2#1 a` Return example: `"3#2#4"`

EXZSCORE

Category	Description
Syntax	`EXZSCORE key member`
Time complexity	O(1)
Command description	Returns the score of a member in the TairZset at the specified key. If the key or member does not exist, it returns nil.
Options	None
Return value	Returns the score of the member as a string. If you use multi-dimensional scores, the format is `"score1#score2#score3#..."`, such as `2#0#6`.
Examples	Command example: `EXZSCORE testkey a` Return example: `"3#2#4"`

EXZRANGE

Category	Description
Syntax	`EXZRANGE key min max [WITHSCORES]`
Time complexity	O(log(N)+M), where N is the number of elements in the TairZset and M is the number of elements returned.
Command description	Returns the specified range of elements from the TairZset at the specified key.
Options	min and max are 0-based indexes. The index of the first element is 0, the index of the second element is 1, and so on. You can use these two parameters to specify a closed interval. Note If an index is negative, it indicates an offset from the end of the returned elements. For example, -1 represents the last element of the key, and -2 represents the second to last element. To query all elements, set min to 0 and max to -1. If the value of min is greater than the index of the last element in the key or the value of max, an empty list is returned. WITHSCORES: Includes the scores of the elements in the return value. The data format of the returned list is `value1, score1, ..., valueN, scoreN`. For example: `1) "b" 2) "1#0#2" 3) "a" 4) "3#2#4"`
Return value	Returns a list of elements in the specified range. If you use the WITHSCORES option, the return value includes the scores of the elements.
Examples	Command example: `EXZRANGE testkey 0 -1 WITHSCORES` Example response: `1) "b" 2) "1#0#2" 3) "a" 4) "3#2#4"`

EXZREVRANGE

Category	Description
Syntax	`EXZREVRANGE key min max [WITHSCORES]`
Time complexity	O(log(N)+M), where N is the number of elements in the TairZset and M is the number of elements returned.
Command description	Returns the specified range of elements from the TairZset at the specified key. Elements are ordered from high to low score. Elements with the same score are ordered in reverse lexicographic order. Note Other than the reverse sorting order, this command is similar to EXZRANGE.
Options	min and max are 0-based indexes. The index of the first element is 0, the index of the second element is 1, and so on. You can use these two parameters to specify a closed interval. Note If an index is negative, it indicates an offset from the end of the returned elements. For example, -1 represents the last element of the key, and -2 represents the second to last element. To query all elements, set min to 0 and max to -1. If the value of min is greater than the index of the last element in the key or the value of max, an empty list is returned. WITHSCORES: Includes the scores of the elements in the return value. The data format of the returned list is `value1, score1, ..., valueN, scoreN`. For example: `1) "b" 2) "1#0#2" 3) "a" 4) "3#2#4"`
Return value	Returns a list of elements in the specified range. If you use the WITHSCORES option, the return value includes the scores of the elements.
Examples	Command example: `EXZREVRANGE testkey 0 -1 WITHSCORES` Return example: `1) "a" 2) "3#2#4" 3) "b" 4) "1#0#2"`

EXZRANGEBYSCORE

Category	Description
Syntax	`EXZRANGEBYSCORE key min max [WITHSCORES] [LIMIT offset count]`
Time complexity	O(log(N)+M), where N is the number of elements in the TairZset and M is the number of elements returned. Note When M is a constant (for example, when you use the LIMIT option to always return the top 10 elements), the complexity can be considered O(log(N)).
Command description	Returns all elements in the TairZset at the specified key with a score between min and max (inclusive). Elements are ordered from low to high score. Elements with the same score are ordered by lexicographic order.
Options	min and max represent the minimum and maximum scores. If the elements in the key use multi-dimensional scores, use a hash symbol (#) to separate the scores for each dimension. Note If you are unsure of the highest and lowest scores of the elements in the key and want to query elements with scores greater than or equal to, or less than or equal to a specific value, set min and max to negative infinity (`-inf`) and positive infinity (`+inf`), respectively. The data range is a closed interval by default. To specify an open interval, add a parenthesis before the score range. For example, `(1 5` returns elements with scores greater than 1 and less than or equal to 5. WITHSCORES: Includes the scores of the elements in the return value. LIMIT offset count: Specifies the number and interval of the returned results. If count is negative, all elements from the offset are returned. Note If offset is large, the entire key must be traversed to locate the offset element before elements can be returned. This increases the time complexity.
Return value	Returns a list of elements in the specified score range. If you use the WITHSCORES option, the return value includes the scores of the elements.
Examples	Command example: `EXZRANGEBYSCORE testkey 0#0#0 6#6#6 WITHSCORES` Return example: `1) "b" 2) "1#0#2" 3) "a" 4) "3#2#4"`

EXZREVRANGEBYSCORE

Category	Description
Syntax	`EXZREVRANGEBYSCORE key max min [WITHSCORES] [LIMIT offset count]`
Time complexity	O(log(N)+M), where N is the number of elements in the TairZset and M is the number of elements returned. Note When M is a constant (for example, when you use the LIMIT option to always return the top 10 elements), the complexity can be considered O(log(N)).
Command description	Returns all elements in the TairZset at the specified key with a score between min and max (inclusive). Unlike the default sorting order in TairZset, this command returns elements ordered from high to low score. Elements with the same score are ordered in reverse lexicographic order. Note Other than the reverse sorting order, this command is similar to EXZRANGEBYSCORE. Note that max comes before min in this command.
Options	min and max represent the minimum and maximum scores. If the elements in the key use multi-dimensional scores, use a hash symbol (#) to separate the scores for each dimension. Note If you are unsure of the highest and lowest scores of the elements in the key and want to query elements with scores greater than or equal to, or less than or equal to a specific value, set min and max to negative infinity (`-inf`) and positive infinity (`+inf`), respectively. The data range is a closed interval by default. To specify an open interval, add a parenthesis before the score range. For example, `(1 5` returns elements with scores greater than 1 and less than or equal to 5. WITHSCORES: Includes the scores of the elements in the return value. LIMIT offset count: Specifies the number and interval of the returned results. If count is negative, all elements from the offset are returned. Note If offset is large, the entire key must be traversed to locate the offset element before elements can be returned. This increases the time complexity.
Return value	Returns a list of elements in the specified score range. If you use the WITHSCORES option, the return value includes the scores of the elements.
Examples	Command example: `EXZREVRANGEBYSCORE testkey 6#6#6 0#0#0 WITHSCORES` Return example: `1) "a" 2) "3#2#4" 3) "b" 4) "1#0#2"`

EXZRANGEBYLEX

Category	Description
Syntax	`EXZRANGEBYLEX key min max [LIMIT offset count]`
Time complexity	O(log(N)+M), where N is the number of elements in the TairZset and M is the number of elements returned. Note When M is a constant (for example, when you use the LIMIT option to return the top 10 elements), the complexity can be considered O(log(N)).
Command description	When all elements in a TairZset have the same score, this command returns elements from the key that are between the min and max lexicographical range. This ensures that elements are sorted by lexicographic order. Note If the elements in the key have different scores, the returned elements are undefined. The command uses the `memcmp() C` function to compare the bytes in two element strings one by one. Elements are sorted from low to high based on the comparison result. If two strings share a common substring, the longer string is considered to have a higher value.
Options	min and max represent the minimum and maximum member names as strings. You must specify the character range. For example: Open interval: Add a parenthesis before the value, such as `(a`. Closed interval: Add a square bracket before the value, such as `[a`. Note Positive and negative infinity are represented by `+` and `-`, respectively. LIMIT offset count: Specifies the number and interval of the returned results. If count is negative, all elements from the offset are returned. Note If offset is large, the entire key must be traversed to locate the offset element before elements can be returned. This increases the time complexity.
Return value	Returns a list of elements whose names are within the specified range.
Examples	Command example: `EXZRANGEBYLEX zzz [a [b` Return example: `1) "aba" 2) "abc"`

EXZREVRANGEBYLEX

Category	Description
Syntax	`EXZREVRANGEBYLEX key max min [LIMIT offset count]`
Time complexity	O(log(N)+M), where N is the number of elements in the TairZset and M is the number of elements returned. Note When M is a constant (for example, when you use the LIMIT option to always return the top 10 elements), the complexity can be considered O(log(N)).
Command description	When all elements in a TairZset have the same score, this command returns elements from the key that are between the max and min lexicographical range. Note Other than the reverse sorting order, this command is similar to EXZRANGEBYLEX. Note that max comes before min in this command.
Options	min and max represent the minimum and maximum member names as strings. You must specify the character range. For example: Open interval: Add a parenthesis before the value, such as `(a`. Closed interval: Add a square bracket before the value, such as `[a`. Note Positive and negative infinity are represented by `+` and `-`, respectively. LIMIT offset count: Specifies the number and interval of the returned results. If count is negative, all elements from the offset are returned. Note If offset is large, the entire key must be traversed to locate the offset element before elements can be returned. This increases the time complexity.
Return value	Returns a list of elements whose names are within the specified range.
Examples	Command example: `EXZREVRANGEBYLEX zzz [b [a` Return example: `1) "abc" 2) "aba"`

EXZREM

Category	Description
Syntax	`EXZREM key member [member ...]`
Time complexity	O(M*log(N)), where N is the number of elements in the TairZset and M is the number of elements to be removed.
Command description	Removes the specified members from the TairZset at the specified key. Non-existent members are ignored. Note If the specified key exists but its data structure is not a TairZset, an error is returned.
Options	None
Return value	Returns the number of members that were removed from the key, not including non-existent members.
Examples	Command example: `EXZREM testkey a` Return example: `(integer) 1`

EXZREMRANGEBYSCORE

Category	Description
Syntax	`EXZREMRANGEBYSCORE key min max`
Time complexity	O(log(N)+M), where N is the number of elements in the TairZset and M is the number of elements to be removed.
Command description	Removes all elements in the TairZset at the specified key with a score between min and max (inclusive).
Options	min and max represent the minimum and maximum scores. If the elements in the key use multi-dimensional scores, use a hash symbol (#) to separate the scores for each dimension. Note If you are unsure of the highest and lowest scores of the elements in the key and want to remove elements with scores greater than or equal to, or less than or equal to a specific value, set min and max to negative infinity (`-inf`) and positive infinity (`+inf`), respectively. The data range is a closed interval by default. To specify an open interval, add a parenthesis before the score range. For example, `EXZREMRANGEBYSCORE (1 5` deletes elements with scores greater than 1 and less than or equal to 5.
Return value	Returns the number of elements removed.
Examples	Command example: `EXZREMRANGEBYSCORE testkey 3#2#4 6#6#6` Return example: `(integer) 1`

EXZREMRANGEBYRANK

Category	Description
Syntax	`EXZREMRANGEBYRANK key start stop`
Time complexity	O(log(N)+M), where N is the number of elements in the TairZset and M is the number of elements removed by the operation.
Command description	Removes all elements in the TairZset at the specified key with a rank between start and stop.
Options	start and stop are 0-based indexes, where 0 represents the element with the lowest score. If an index is negative, it represents an offset from the element with the highest score. For example, -1 is the element with the highest score, and -2 is the element with the second-highest score.
Return value	The number of elements removed.
Examples	Command example: `EXZREMRANGEBYRANK testkey 0 1EXZREVRANGEBYSCORE` Return example: `(integer) 1`

EXZREMRANGEBYLEX

Category	Description
Syntax	`EXZREMRANGEBYLEX key min max`
Time complexity	O(log(N)+M), where N is the number of elements in the TairZset and M is the number of elements removed by the operation.
Command description	When all elements in a TairZset have the same score, this command removes elements from the key that are between the max and min lexicographical range. This ensures that elements are sorted by lexicographic order. Note If you run this command and the EXZRANGEBYLEX command with the same min and max parameter values, this command removes the same elements that the EXZRANGEBYLEX command returns.
Options	min and max represent the minimum and maximum member names as strings. You must specify the character range. For example: Open interval: Add a parenthesis before the value, such as `(a`. Closed interval: Add a square bracket before the value, such as `[a`.
Return value	The number of elements removed.
Examples	Command example: `EXZREMRANGEBYLEX [a [b` Return example: `(integer) 2`

EXZCARD

Category	Description
Syntax	`EXZCARD key`
Time complexity	O(1)
Command description	Returns the cardinality (number of elements) of the TairZset at the specified key.
Options	None
Return value	Returns the number of elements in the key. If the key does not exist, it returns 0.
Examples	Command example: `EXZCARD testkey` Return example: `(integer) 2`

EXZRANK

Category	Description
Syntax	`EXZRANK key member`
Time complexity	O(log(N))
Command description	Returns the rank of a member in the TairZset at the specified key, with scores ordered from low to high. The rank (or index) is 0-based, so the member with the lowest score has a rank of 0.
Options	None
Return value	If the specified member exists in the key, returns the rank of the member as an integer. If the key or the member in the key does not exist, returns nil.
Examples	Command example: `EXZRANK testkey b` Return example: `(integer) 0`

EXZREVRANK

Category	Description
Syntax	`EXZREVRANK key member`
Time complexity	O(log(N))
Command description	Returns the rank of a member in the TairZset at the specified key. The results are ordered from high to low score. The rank (or index) is 0-based, so the member with the highest score has a rank of 0. Note Other than the reverse sorting order, this command is similar to EXZRANK.
Options	None
Return value	If the specified member exists in the key, returns the rank of the member as an integer. If the key or the member in the key does not exist, returns nil.
Examples	Command example: `EXZREVRANK testkey b` Return example:(integer) 1 `(integer) 1`

EXZCOUNT

Category	Description
Syntax	`EXZCOUNT key min max`
Time complexity	O(log(N)), where N is the number of elements in the TairZset. Note Because the query range is obtained based on element ranks, the amount of work involved in this operation is not proportional to the size of the query range.
Command description	Returns the number of elements in the TairZset at the specified key with a score between min and max.
Options	min and max represent the minimum and maximum scores. If the elements in the key use multi-dimensional scores, use a hash symbol (#) to separate the scores for each dimension. Note If you are unsure of the highest and lowest scores of the elements in the key and want to query elements with scores greater than or equal to, or less than or equal to a specific value, set min and max to negative infinity and positive infinity, respectively. The data range is a closed interval by default. To specify an open interval, add a parenthesis before the score range. For example, `(1 5` returns elements with scores greater than 1 and less than or equal to 5.
Return value	Returns the number of elements (as an integer) within the specified score range.
Examples	Command example: `EXZCOUNT testkey (1#0#2 6#6#6` Return example: `(integer) 1`

EXZLEXCOUNT

Category	Description
Syntax	`EXZLEXCOUNT key min max`
Time complexity	O(log(N)), where N is the number of elements in the TairZset. Note Because the query range is obtained based on element ranks, the amount of work involved in this operation is not proportional to the size of the query range.
Command description	When all elements in a TairZset have the same score, this command returns the number of elements at the specified key that are between the min and max lexicographical range. This ensures that elements are sorted by lexicographic order. Note If the elements in the key have different scores, the returned elements are undefined. The command uses the `memcmp() C` function to compare the bytes in two element strings one by one. Elements are sorted from low to high based on the comparison result. If two strings share a common substring, the longer string is considered to have a higher value.
Options	min and max represent the minimum and maximum member names as strings. You must specify the character range. For example: Open interval: Add a parenthesis before the value, such as `(a`. Closed interval: Add a square bracket before the value, such as `[a`.
Return value	Returns the number of elements (as an integer) within the specified score range.
Examples	Command example: `EXZLEXCOUNT zzz [a [b` Return example: `(integer) 2`

EXZRANKBYSCORE

Category	Description
Syntax	`EXZRANKBYSCORE key score`
Time complexity	O(log(N))
Command description	Calculates the rank of a given score in the TairZset at the specified key, with scores ordered from low to high. The rank (or index) is 0-based, so the member with the lowest score has a rank of 0. Note If the specified score does not exist, the command returns the prospective rank of that score in the TairZset. If the specified score already exists, Tair ranks the specified score before the existing score by default.
Options	None
Return value	Returns the rank of the specified score in the key.
Examples	Command example: `EXZRANKBYSCORE testkey 2#0#2` Return example: `(integer) 1`

EXZREVRANKBYSCORE

Category	Description
Syntax	`EXZREVRANKBYSCORE key score`
Time complexity	O(log(N))
Command description	Calculates the rank of a given score in the TairZset at the specified key, with scores ordered from high to low. The rank (or index) is 0-based, so the member with the highest score has a rank of 0. Note If the specified score does not exist, the command returns the prospective rank of that score in the TairZset. If the specified score already exists, Tair ranks the specified score after the existing score by default.
Options	None
Return value	Returns the rank of the specified score in the key.
Examples	Command example: `EXZREVRANKBYSCORE testkey 2#0#2` Return example: `(integer) 1`