io.lettuce.core.search.aggregateutils

Class GroupBy<K,V>

java.lang.Object

io.lettuce.core.search.aggregateutils.GroupBy<K,V>

Type Parameters:

K - Key type.

V - Value type.

All Implemented Interfaces:

PostProcessingOperation<K,V>

@Experimental
public class GroupBy<K,V>
extends Object
implements PostProcessingOperation<K,V>

GROUPBY post-processing operation. Groups results by one or more properties with reducer functions.

Groups the results in the pipeline based on one or more properties. Each group should have at least one reducer function that handles the group entries, either counting them or performing multiple aggregate operations.

Example Usage:

 
 {
     @code
     // Group by category and count items
     GroupBy groupBy = GroupBy.of("category").reduce(Reducers.count().as("item_count"));

     // Group by multiple fields with multiple reducers
     GroupBy complexGroup = GroupBy.of("category", "brand").reduce(Reducers.count().as("count"))
             .reduce(Reducers.avg("@price").as("avg_price"));
 }
 

Since:

7.5

Author:

Aleksandar Todorov

See Also:

Reducer, Reducers, ReduceFunction, PostProcessingOperation

Constructor Summary

Constructors

Constructor and Description
GroupBy(List<K> properties) Creates a new GROUPBY operation.

Method Summary

Modifier and Type	Method and Description
void	build(CommandArgs<K,V> args) Build the operation arguments into the command args.
static <K,V> GroupBy<K,V>	of(K... properties) Static factory method to create a GroupBy instance.
GroupBy<K,V>	reduce(Reducer<K> reducer) Add a reducer to this GROUPBY operation.

Methods inherited from class java.lang.Object

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

Constructor Detail

GroupBy

public GroupBy(List<K> properties)

Creates a new GROUPBY operation.

Parameters:

properties - the properties to group by

Method Detail

of

@SafeVarargs
public static <K,V> GroupBy<K,V> of(K... properties)

Static factory method to create a GroupBy instance.

Type Parameters:

K - Key type

V - Value type

Parameters:

properties - the properties to group by

Returns:

new GroupBy instance

reduce

public GroupBy<K,V> reduce(Reducer<K> reducer)

Add a reducer to this GROUPBY operation.

Parameters:

reducer - the reducer to add

Returns:

this GroupBy instance

build

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

Description copied from interface: PostProcessingOperation

Build the operation arguments into the command args.

Specified by:

build in interface PostProcessingOperation<K,V>

Parameters:

args - the command args to build into