io.lettuce.core.search.arguments

Class AggregateArgs.Reducer<K,V>

java.lang.Object

io.lettuce.core.search.arguments.AggregateArgs.Reducer<K,V>

Enclosing class:

AggregateArgs<K,V>

public static class AggregateArgs.Reducer<K,V>
extends Object

Represents a REDUCE function in a GROUPBY clause.

Reducers handle group entries in a GROUPBY operation, performing aggregate operations like counting, summing, averaging, or finding min/max values. Each reducer can have an optional alias using the AS keyword.

Example Usage:

 
 {
     @code
     // Count items in each group
     Reducer count = Reducer.count().as("item_count");

     // Sum numeric values
     Reducer totalSales = Reducer.sum("@sales").as("total_sales");

     // Calculate average
     Reducer avgPrice = Reducer.avg("@price").as("average_price");

     // Find extremes
     Reducer maxScore = Reducer.max("@score").as("highest_score");
     Reducer minPrice = Reducer.min("@price").as("lowest_price");

     // Count distinct values
     Reducer uniqueUsers = Reducer.countDistinct("@user_id").as("unique_users");
 }
 

Available Reducer Functions:

• COUNT - Count the number of records in the group
• SUM - Sum all numeric values of a field
• AVG - Calculate the average of numeric values
• MIN - Find the minimum value
• MAX - Find the maximum value
• COUNT_DISTINCT - Count unique values of a field

If no alias is provided using as(), the resulting field name will be the function name combined with the field name (e.g., "count_distinct(@user_id)").

Constructor Summary

Constructors

Constructor and Description
Reducer(String function, List<V> args)

Method Summary

Modifier and Type	Method and Description
AggregateArgs.Reducer<K,V>	as(K alias)
static <K,V> AggregateArgs.Reducer<K,V>	avg(V field) Static factory method to create an AVG reducer.
void	build(CommandArgs<K,V> args)
static <K,V> AggregateArgs.Reducer<K,V>	count() Static factory method to create a COUNT reducer.
static <K,V> AggregateArgs.Reducer<K,V>	countDistinct(V field) Static factory method to create a COUNT_DISTINCT reducer.
static <K,V> AggregateArgs.Reducer<K,V>	max(V field) Static factory method to create a MAX reducer.
static <K,V> AggregateArgs.Reducer<K,V>	min(V field) Static factory method to create a MIN reducer.
static <K,V> AggregateArgs.Reducer<K,V>	sum(V field) Static factory method to create a SUM reducer.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Reducer

public Reducer(String function,
               List<V> args)

Method Detail

as

public AggregateArgs.Reducer<K,V> as(K alias)

count

public static <K,V> AggregateArgs.Reducer<K,V> count()

Static factory method to create a COUNT reducer.

Type Parameters:

K - Key type

V - Value type

Returns:

new COUNT Reducer instance

sum

public static <K,V> AggregateArgs.Reducer<K,V> sum(V field)

Static factory method to create a SUM reducer.

Type Parameters:

K - Key type

V - Value type

Parameters:

field - the field to sum

Returns:

new SUM Reducer instance

avg

public static <K,V> AggregateArgs.Reducer<K,V> avg(V field)

Static factory method to create an AVG reducer.

Type Parameters:

K - Key type

V - Value type

Parameters:

field - the field to average

Returns:

new AVG Reducer instance

min

public static <K,V> AggregateArgs.Reducer<K,V> min(V field)

Static factory method to create a MIN reducer.

Type Parameters:

K - Key type

V - Value type

Parameters:

field - the field to find minimum

Returns:

new MIN Reducer instance

max

public static <K,V> AggregateArgs.Reducer<K,V> max(V field)

Static factory method to create a MAX reducer.

Type Parameters:

K - Key type

V - Value type

Parameters:

field - the field to find maximum

Returns:

new MAX Reducer instance

countDistinct

public static <K,V> AggregateArgs.Reducer<K,V> countDistinct(V field)

Static factory method to create a COUNT_DISTINCT reducer.

Type Parameters:

K - Key type

V - Value type

Parameters:

field - the field to count distinct values

Returns:

new COUNT_DISTINCT Reducer instance

build

public void build(CommandArgs<K,V> args)