Redis zcount 命令
ZCOUNT key min max
Returns the number of elements in the sorted set at
key with a score between
max arguments have the same semantic as described for ZRANGEBYSCORE.
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.
Integer reply: the number of elements in the specified score range.
redis> ZADD myzset 2 “two”
redis> ZADD myzset 3 “three”
redis> ZCOUNT myzset -inf +inf
redis> ZCOUNT myzset (1 3