io.lettuce.core.search.arguments

Class AggregateArgs.Reducer

java.lang.Object

io.lettuce.core.search.arguments.AggregateArgs.Reducer

Direct Known Subclasses:

AggregateArgs.CollectReducer

Enclosing class:

AggregateArgs

public static class AggregateArgs.Reducer
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<String> args)

Method Summary

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

Method Detail

as

public AggregateArgs.Reducer as(String alias)

count

public static AggregateArgs.Reducer count()

Static factory method to create a COUNT reducer.

Returns:

new COUNT Reducer instance

sum

public static AggregateArgs.Reducer sum(String field)

Static factory method to create a SUM reducer.

Parameters:

field - the field to sum

Returns:

new SUM Reducer instance

avg

public static AggregateArgs.Reducer avg(String field)

Static factory method to create an AVG reducer.

Parameters:

field - the field to average

Returns:

new AVG Reducer instance

min

public static AggregateArgs.Reducer min(String field)

Static factory method to create a MIN reducer.

Parameters:

field - the field to find minimum

Returns:

new MIN Reducer instance

max

public static AggregateArgs.Reducer max(String field)

Static factory method to create a MAX reducer.

Parameters:

field - the field to find maximum

Returns:

new MAX Reducer instance

countDistinct

public static AggregateArgs.Reducer countDistinct(String field)

Static factory method to create a COUNT_DISTINCT reducer.

Parameters:

field - the field to count distinct values

Returns:

new COUNT_DISTINCT Reducer instance

collect

@Experimental
public static AggregateArgs.CollectReducer collect()

Static factory method to create a COLLECT reducer.

COLLECT gathers per-document projections within a GROUPBY group and returns them as an array of per-entry maps under the reducer alias, optionally sorted and bounded. Configure the projected fields via fields(...) or fieldsAll(), then optionally chain sortBy(...) and limit(...) before calling as(...).

The collected column is a FieldValue of kind FieldValue.Kind.ARRAY with one element per collected entry; read the entries via asList() and each entry via asMap(), which normalizes the protocol-specific entry shape.

Experimental. Both the underlying Redis Search feature and this API may change. COLLECT is gated behind search-enable-unstable-features; enable it on the server (for example via CONFIG SET search-enable-unstable-features yes) before issuing aggregations that use this reducer, otherwise the server replies with an error.

Returns:

new AggregateArgs.CollectReducer instance

Since:

7.8

See Also:

AggregateArgs.CollectReducer

build

public void build(CommandArgs<?,?> args)