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Elasticsearch subproject :server
/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the Elastic License
* 2.0 and the Server Side Public License, v 1; you may not use this file except
* in compliance with, at your election, the Elastic License 2.0 or the Server
* Side Public License, v 1.
*/
package org.elasticsearch.search.slice;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.ConstantScoreScorer;
import org.apache.lucene.search.ConstantScoreWeight;
import org.apache.lucene.search.DocIdSetIterator;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.ScoreMode;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.Weight;
import org.elasticsearch.search.sort.FieldSortBuilder;
import java.io.IOException;
/**
* A {@link SliceQuery} that partitions documents based on their Lucene ID. To take
* advantage of locality, each slice holds a contiguous range of document IDs.
*
* NOTE: Because the query relies on Lucene document IDs, it is not stable across
* readers. It's intended for scenarios where the reader doesn't change, like in
* a point-in-time search.
*/
public final class DocIdSliceQuery extends SliceQuery {
/**
* @param id The id of the slice
* @param max The maximum number of slices
*/
public DocIdSliceQuery(int id, int max) {
super(FieldSortBuilder.DOC_FIELD_NAME, id, max);
}
@Override
public Weight createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost) throws IOException {
int maxDoc = searcher.getTopReaderContext().reader().maxDoc();
int remainder = maxDoc % getMax();
int quotient = maxDoc / getMax();
int sliceStart;
int sliceSize;
if (getId() < remainder) {
sliceStart = (quotient + 1) * getId();
sliceSize = quotient + 1;
} else {
sliceStart = remainder * (quotient + 1) + (getId() - remainder) * quotient;
sliceSize = quotient;
}
return new ConstantScoreWeight(this, boost) {
@Override
public Scorer scorer(LeafReaderContext context) {
DocIdSetIterator iterator = createIterator(context, sliceStart, sliceStart + sliceSize);
return new ConstantScoreScorer(this, boost, scoreMode, iterator);
}
private static DocIdSetIterator createIterator(LeafReaderContext context, int sliceStart, int sliceEnd) {
int leafStart = context.docBase;
int leafEnd = context.docBase + context.reader().maxDoc();
// There is no overlap with this segment, so return empty iterator
if (leafEnd <= sliceStart || leafStart >= sliceEnd) {
return DocIdSetIterator.empty();
}
int start = Math.max(leafStart, sliceStart) - context.docBase;
int end = Math.min(leafEnd, sliceEnd) - context.docBase;
return DocIdSetIterator.range(start, end);
}
@Override
public boolean isCacheable(LeafReaderContext ctx) {
return false;
}
};
}
}