com.hazelcast.query.PartitionPredicate Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2024, Hazelcast, Inc. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hazelcast.query;
import com.hazelcast.internal.serialization.BinaryInterface;
import com.hazelcast.spi.annotation.NamespacesSupported;
import java.util.Collection;
import java.util.Collections;
/**
* A {@link Predicate} that restricts the execution of a {@link Predicate} to specific partitions.
*
* This can help to speed up query execution since only a subset of all partitions needs to be queried.
*
* This predicate only has effect if used as an outermost predicate.
*
* @param type of the entry key
* @param type of the entry value
* @see Predicates#partitionPredicate(Object, Predicate)
*/
@NamespacesSupported
@BinaryInterface
public interface PartitionPredicate extends Predicate {
/**
* Returns the partition keys that determine the partitions the {@linkplain
* #getTarget() target} {@link Predicate} is going to execute on.
*
* A default implementation of {@linkplain #getPartitionKeys() partition keys}
* that wraps the {@linkplain #getPartitionKey() partition key} in a singleton
* collection is provided for backwards compatibility.
*
* @return the partition keys
* @since 5.2
*/
default Collection getPartitionKeys() {
return Collections.singleton(getPartitionKey());
}
/**
* Returns a random partition key from the {@linkplain #getPartitionKeys() collection}.
* This is useful for client message routing to cluster instances.
* If there is a single value in the collection it is always returned as-is to be backwards
* compatible with older versions of PartitionPredicate.
*
* @return the single key
*/
Object getPartitionKey();
/**
* Returns the target {@link Predicate}.
*/
Predicate getTarget();
}