原文

http://redis.io/commands/zlexcount

简介

Count the number of members in a sorted set between a given lexicographical range.

计算有序集合中在指定词典范围内的成员的数量。

语法

ZLEXCOUNT key min max

版本

Available since 2.8.9.

自2.8.9版本可用。

时间复杂度

Time complexity: O(log(N)) with N being the number of elements in the sorted set.

O(log(N))：N是有序集合中元素的数量。

描述

When all the elements in a sorted set are inserted with the same score, in order to force lexicographical ordering, this command returns the number of elements in the sorted set at key with a value between min and max.

当有序集合中插入的所有元素的分数相同时，为了强制进行词典排序，这个命令返回值在min到max之间的元素的数量。

The min and max arguments have the same meaning as described for ZRANGEBYLEX.

参数min和max与ZRANGEBYLEX命令有相同的含义。

Note: the command has a complexity of just O(log(N)) because it uses elements ranks (see ZRANK) to get an idea of the range. Because of this there is no need to do a work proportional to the size of the range.

返回值

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

Integer：指定值范围内的元素的数量。

例子

redis>  ZADD myzset 0 a 0 b 0 c 0 d 0 e
(integer) 5
redis>  ZADD myzset 0 f 0 g
(integer) 2
redis>  ZLEXCOUNT myzset - +
(integer) 7
redis>  ZLEXCOUNT myzset [b [f
(integer) 5
redis>