com.hazelcast.jet.pipeline

Class JoinClause<K,T0,T1,T1_OUT>

java.lang.Object

com.hazelcast.jet.pipeline.JoinClause<K,T0,T1,T1_OUT>

Type Parameters:

K - the type of the join key

T0 - the type of the left-hand stream item

T1 - the type of the right-hand stream item

T1_OUT - the result type of the right-hand projection function

All Implemented Interfaces:

Serializable

public final class JoinClause<K,T0,T1,T1_OUT>
extends Object
implements Serializable

Specifies how to join an enriching stream to the primary stream in a hash-join operation. It holds three primitives:

1. left-hand key extractor: extracts the join key from the primary stream
2. right-hand key extractor: extracts the join key from the enriching stream
3. right-hand projection function: maps the enriching stream item to the item that will be in the result of the join operation.

The primary use case for the projection function is enrichment from a map source, such as Sources.map(java.lang.String). The enriching stream consists of map entries, but the result should contain just the values. In this case the projection function should be Entry::getValue. There is direct support for this case with the method joinMapEntries(FunctionEx).

Since:

Jet 3.0

See Also:

Serialized Form

Method Summary

Modifier and Type	Method and Description
static <K,T0,T1_OUT> JoinClause<K,T0,Map.Entry<K,T1_OUT>,T1_OUT>	joinMapEntries(FunctionEx<? super T0,? extends K> leftKeyFn) A shorthand factory for the common case of hash-joining with a stream of map entries.
FunctionEx<? super T0,? extends K>	leftKeyFn() Returns the left-hand key extractor function.
static <K,T0,T1> JoinClause<K,T0,T1,T1>	onKeys(FunctionEx<? super T0,? extends K> leftKeyFn, FunctionEx<? super T1,? extends K> rightKeyFn) Constructs and returns a join clause with the supplied left-hand and right-hand key extractor functions, and with an identity right-hand projection function.
<T1_NEW_OUT> JoinClause<K,T0,T1,T1_NEW_OUT>	projecting(FunctionEx<? super T1,? extends T1_NEW_OUT> rightProjectFn) Returns a copy of this join clause, but with the right-hand projection function replaced with the supplied one.
FunctionEx<? super T1,? extends K>	rightKeyFn() Returns the right-hand key extractor function.
FunctionEx<? super T1,? extends T1_OUT>	rightProjectFn() Returns the right-hand projection function.

Methods inherited from class java.lang.Object

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

Method Detail

onKeys

public static <K,T0,T1> JoinClause<K,T0,T1,T1> onKeys(FunctionEx<? super T0,? extends K> leftKeyFn,
                                                      FunctionEx<? super T1,? extends K> rightKeyFn)

Constructs and returns a join clause with the supplied left-hand and right-hand key extractor functions, and with an identity right-hand projection function.

The given functions must be stateless and cooperative.

joinMapEntries

public static <K,T0,T1_OUT> JoinClause<K,T0,Map.Entry<K,T1_OUT>,T1_OUT> joinMapEntries(FunctionEx<? super T0,? extends K> leftKeyFn)

A shorthand factory for the common case of hash-joining with a stream of map entries. The right key extractor is Map.Entry::getKey and the right-hand projection function is Map.Entry::getValue.

Type Parameters:

K - the type of the key

T0 - the type of the primary stream

T1_OUT - the type of the enriching stream's entry value

Parameters:

leftKeyFn - the function to extract the key from the primary stream. It must be stateless and cooperative.

projecting

public <T1_NEW_OUT> JoinClause<K,T0,T1,T1_NEW_OUT> projecting(FunctionEx<? super T1,? extends T1_NEW_OUT> rightProjectFn)

Returns a copy of this join clause, but with the right-hand projection function replaced with the supplied one.

The given function must be stateless and cooperative.

leftKeyFn

public FunctionEx<? super T0,? extends K> leftKeyFn()

Returns the left-hand key extractor function.

rightKeyFn

public FunctionEx<? super T1,? extends K> rightKeyFn()

Returns the right-hand key extractor function.

rightProjectFn

public FunctionEx<? super T1,? extends T1_OUT> rightProjectFn()

Returns the right-hand projection function.