org.elasticsearch.index.codec.postingsformat.DirectPostingsFormatProvider Maven / Gradle / Ivy
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* Licensed to ElasticSearch and Shay Banon under one
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* distributed with this work for additional information
* regarding copyright ownership. ElasticSearch 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
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* under the License.
*/
package org.elasticsearch.index.codec.postingsformat;
import org.apache.lucene.codecs.PostingsFormat;
import org.apache.lucene.codecs.memory.DirectPostingsFormat;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.inject.assistedinject.Assisted;
import org.elasticsearch.common.settings.Settings;
/**
* A {@link PostingsFormatProvider} for {@link DirectPostingsFormat}. This
* postings format uses an on-disk storage for its terms and posting lists and
* streams its data during segment merges but loads its entire postings, terms
* and positions into memory for faster search performance. This format has a
* significant memory footprint and should be used with care. This postings
* format offers the following parameters:
*
* - min_skip_count: the minimum number terms with a shared prefix to
* allow a skip pointer to be written. the default is 8
*
* - low_freq_cutoff: terms with a lower document frequency use a
* single array object representation for postings and positions.
*
*
* @see DirectPostingsFormat
*
*/
public class DirectPostingsFormatProvider extends AbstractPostingsFormatProvider {
private final int minSkipCount;
private final int lowFreqCutoff;
private final DirectPostingsFormat postingsFormat;
@Inject
public DirectPostingsFormatProvider(@Assisted String name, @Assisted Settings postingsFormatSettings) {
super(name);
this.minSkipCount = postingsFormatSettings.getAsInt("min_skip_count", 8); // See DirectPostingsFormat#DEFAULT_MIN_SKIP_COUNT
this.lowFreqCutoff = postingsFormatSettings.getAsInt("low_freq_cutoff", 32); // See DirectPostingsFormat#DEFAULT_LOW_FREQ_CUTOFF
this.postingsFormat = new DirectPostingsFormat(minSkipCount, lowFreqCutoff);
}
public int minSkipCount() {
return minSkipCount;
}
public int lowFreqCutoff() {
return lowFreqCutoff;
}
@Override
public PostingsFormat get() {
return postingsFormat;
}
}