/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.solr.handler.component;
import org.apache.solr.search.SolrIndexSearcher;
import java.util.Comparator;
import java.io.IOException;
/**
* The MergeStrategy class defines custom merge logic for distributed searches.
*
* <b>Note: This API is experimental and may change in non backward-compatible ways in the future</b>
**/
public interface MergeStrategy {
/**
* merge defines the merging behaving of results that are collected from the
* shards during a distributed search.
*
**/
public void merge(ResponseBuilder rb, ShardRequest sreq);
/**
* mergesIds must return true if the merge method merges document ids from the shards.
* If it merges other output from the shards it must return false.
* */
public boolean mergesIds();
/**
* handlesMergeFields must return true if the MergeStrategy
* implements a custom handleMergeFields(ResponseBuilder rb, SolrIndexSearch searcher)
* */
public boolean handlesMergeFields();
/**
* Implement handleMergeFields(ResponseBuilder rb, SolrIndexSearch searcher) if
* your merge strategy needs more complex data then the sort fields provide.
* */
public void handleMergeFields(ResponseBuilder rb, SolrIndexSearcher searcher) throws IOException;
/**
* Defines the order that the mergeStrategies are applied. Lower costs are applied first.
* */
public int getCost();
final Comparator MERGE_COMP = (o1, o2) -> {
MergeStrategy m1 = (MergeStrategy) o1;
MergeStrategy m2 = (MergeStrategy) o2;
return m1.getCost() - m2.getCost();
};
}