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DiceDB

ZPOPMIN

The ZPOPMIN command in DiceDB is used to remove and return the members with the lowest scores from the sorted set data structure at the specified key. If a count is provided, it returns up to that number of members with the lowest scores, removing them from the set.

Syntax

Terminal window
ZPOPMIN key [count]

Parameters

ParameterDescriptionTypeRequired
keyThe name of the sorted set. If it does not exist, an empty array is returned.StringYes
countThe count argument specifies the number of members to return with the lowest scores.IntegerNo

Return values

ConditionReturn Value
If the key is of valid type and records are presentList of members including their scores
If the key does not exist or if the sorted set is empty(empty list or set)

Behaviour

  • The command first checks if the specified key exists.
  • If the key does not exist, an empty array is returned.
  • If the key exists but is not a sorted set, an error is returned.
  • If the count argument is specified, up to that number of members with the lowest scores are returned and removed.
  • The returned array contains the members and their corresponding scores in the order of lowest to highest.

Errors

  1. Wrong type of value or key:

    • Error Message: (error) WRONGTYPE Operation against a key holding the wrong kind of value
    • Occurs when trying to use the command on a key that is not a sorted set.

  2. Invalid syntax or conflicting options:

    • Error Message: (error) ERROR wrong number of arguments for 'zpopmin' command
    • Occurs when the command syntax is incorrect or missing required parameters.

  3. Non-integer value for count“:

    • Error Message : (error) ERR value is not an integer or out of range
    • Occurs when the count argument passed to the command is not an integer.

Examples

Basic Usage

Popping the member with the lowest score from an existing sorted set:

Terminal window
127.0.0.1:7379> ZADD myzset 1 member1 2 member2 3 member3
(integer) 3
127.0.0.1:7379> ZPOPMIN myzset
1) 1 "member1"

Non-Existing Key

Attempting to pop the member with the lowest score from a non-existent sorted set:

Terminal window
127.0.0.1:7379> ZPOPMIN NON_EXISTENT_KEY
(empty array)

With count argumment

Popping multiple members with the lowest scores using the count argument:

Terminal window
127.0.0.1:7379> ZADD myzset 1 member1 2 member2 3 member3
(integer) 3
127.0.0.1:7379> ZPOPMIN myzset 2
1) 1 "member1"
2) 2 "member2"

Count Argument but Multiple Members Have the Same Score

Popping members when multiple members share the same score:

Terminal window
127.0.0.1:7379> ZADD myzset 1 member1 1 member2 1 member3
(integer) 3
127.0.0.1:7379> ZPOPMIN myzset 2
1) 1 "member1"
2) 1 "member2"

Negative Count Argument

Attempting to pop members using a negative count argument:

Terminal window
127.0.0.1:7379> ZADD myzset 1 member1 2 member2 3 member3
(integer) 3
127.0.0.1:7379> ZPOPMIN myzset -1
(empty array)

Floating-Point Scores

Popping members with floating-point scores:

Terminal window
127.0.0.1:7379> ZADD myzset 1.5 member1 2.7 member2 3.8 member3
(integer) 3
127.0.0.1:7379> ZPOPMIN myzset
1) 1.5 "member1"

Wrong number of arguments

Attempting to pop from a key that is not a sorted set:

Terminal window
127.0.0.1:7379> SET stringkey "string_value"
OK
127.0.0.1:7379> ZPOPMIN stringkey
(error) WRONGTYPE Operation against a key holding the wrong kind of value

Invalid Usage

Using an invalid (non-integer) count argument:

Terminal window
127.0.0.1:7379> ZADD myzset 1 member1
(integer) 1
127.0.0.1:7379> ZPOPMIN myzset INCORRECT_COUNT_ARGUMENT
(error) ERR value is not an integer or out of range

Wrong Type of Key

Attempting to pop from a key that is not a sorted set:

Terminal window
127.0.0.1:7379> SET stringkey "string_value"
OK
127.0.0.1:7379> ZPOPMIN stringkey
(error) WRONGTYPE Operation against a key holding the wrong kind of value