ZCOUNT

The ZCOUNT command in DiceDB counts the number of members in a sorted set at the specified key whose scores fall within a given range. The command takes three arguments: the key of the sorted set, the minimum score, and the maximum score. If the key does not exist or contains no members, the command returns 0. It allows for flexible range queries by using special values like -inf and +inf to specify unbounded limits.

Syntax

ZCOUNT key min max

Parameters

Parameter	Description	Type	Required
key	The name of the sorted set to operate on.	String	Yes
min	Minimum score (inclusive) of the range to count.	Int	Yes
max	Maximum score (inclusive) of the range to count.	Int	Yes

Return Values

Condition	Return Value
If the key exists and is a sorted set	Returns the count of elements in the specified range.
If the key does not exist	Returns 0.
If the key is not a sorted set	Returns an error.

Behaviour

Retrieves the sorted set associated with the given key. Counts all elements whose scores fall between the given min and max (inclusive). If the key does not exist, it behaves as if it is an empty sorted set and returns 0. If the key is not of the sorted set type, an error is returned.

Errors

1. Wrong Type:
   • Message: (error) WRONGTYPE Operation against a key holding the wrong kind of value
2. Wrong Argument Count:
   • Message: (error) ERROR wrong number of arguments for 'zcount' command

Example Usage

127.0.0.1:7379> ZCOUNT NON_EXISTENT_KEY 0 100
0

127.0.0.1:7379> ZADD myzset 10 member1 20 member2 30 member3
(integer) 3
127.0.0.1:7379> ZCOUNT myzset 15 25
1

127.0.0.1:7379> ZCOUNT myzset 50 100
0

127.0.0.1:7379> ZCOUNT myzset 30 10
0

Invalid usage

127.0.0.1:7379> ZCOUNT myzset
(error) ERROR wrong number of arguments for 'zcount' command

127.0.0.1:7379> ZCOUNT myzset "invalid" 100
(integer) 0