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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.search.significance;
import com.yahoo.component.annotation.Inject;
import com.yahoo.component.chain.dependencies.Before;
import com.yahoo.component.chain.dependencies.Provides;
import com.yahoo.language.Language;
import com.yahoo.language.significance.SignificanceModel;
import com.yahoo.language.significance.SignificanceModelRegistry;
import com.yahoo.prelude.query.CompositeItem;
import com.yahoo.prelude.query.Item;
import com.yahoo.prelude.query.NullItem;
import com.yahoo.prelude.query.WordItem;
import com.yahoo.search.Query;
import com.yahoo.search.Result;
import com.yahoo.search.Searcher;
import com.yahoo.search.query.ranking.Significance;
import com.yahoo.search.result.ErrorMessage;
import com.yahoo.search.schema.RankProfile;
import com.yahoo.search.schema.Schema;
import com.yahoo.search.schema.SchemaInfo;
import com.yahoo.search.searchchain.Execution;
import java.util.HashSet;
import java.util.Optional;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.stream.Collectors;
import static com.yahoo.prelude.querytransform.StemmingSearcher.STEMMING;
/**
* Sets significance values on word items in the query tree.
*
* @author Marius Arhaug
*/
@Provides(SignificanceSearcher.SIGNIFICANCE)
@Before(STEMMING)
public class SignificanceSearcher extends Searcher {
public final static String SIGNIFICANCE = "Significance";
private static final Logger log = Logger.getLogger(SignificanceSearcher.class.getName());
private final SignificanceModelRegistry significanceModelRegistry;
private final SchemaInfo schemaInfo;
@Inject
public SignificanceSearcher(SignificanceModelRegistry significanceModelRegistry, SchemaInfo schemaInfo) {
this.significanceModelRegistry = significanceModelRegistry;
this.schemaInfo = schemaInfo;
}
@Override
public Result search(Query query, Execution execution) {
var ranking = query.getRanking();
var rankProfileName = query.getRanking().getProfile();
Optional<Boolean> useSignificanceModelOverride = ranking.getSignificance().getUseModel();
if (useSignificanceModelOverride.isPresent() && !useSignificanceModelOverride.get()) {
return execution.search(query);
}
if (useSignificanceModelOverride.isPresent()) {
return calculateAndSetSignificance(query, execution);
}
// Determine significance setup per schema for the given rank profile
var perSchemaSetup = schemaInfo.newSession(query).schemas().stream()
.collect(Collectors.toMap(Schema::name, schema ->
// Fallback to disabled if the rank profile is not found in the schema
// This will result in a failure later (in a "backend searcher") anyway.
Optional.ofNullable(schema.rankProfiles().get(rankProfileName))
.map(RankProfile::useSignificanceModel).orElse(false)));
log.log(Level.FINE, () -> "Significance setup per schema: " + perSchemaSetup);
var uniqueSetups = new HashSet<>(perSchemaSetup.values());
// Fail if the significance setup for the selected schemas are conflicting
if (uniqueSetups.size() > 1) {
var result = new Result(query);
result.hits().addError(
ErrorMessage.createIllegalQuery(
("Inconsistent 'significance' configuration for the rank profile '%s' in the schemas %s. " +
"Use 'restrict' to limit the query to a subset of schemas " +
"(https://docs.vespa.ai/en/schemas.html#multiple-schemas). " +
"Specify same 'significance' configuration for all selected schemas " +
"(https://docs.vespa.ai/en/reference/schema-reference.html#significance).")
.formatted(rankProfileName, perSchemaSetup.keySet())));
return result;
}
if (perSchemaSetup.isEmpty()) return execution.search(query);
var useSignificanceModel = uniqueSetups.iterator().next();
if (!useSignificanceModel) return execution.search(query);
return calculateAndSetSignificance(query, execution);
}
private Result calculateAndSetSignificance(Query query, Execution execution) {
try {
var significanceModel = getSignificanceModelFromQueryLanguage(query);
log.log(Level.FINE, () -> "Got model for language %s: %s"
.formatted(query.getModel().getParsingLanguage(), significanceModel.getId()));
setIDF(query.getModel().getQueryTree().getRoot(), significanceModel);
return execution.search(query);
} catch (IllegalArgumentException e) {
var result = new Result(query);
result.hits().addError(
ErrorMessage.createIllegalQuery(e.getMessage()));
return result;
}
}
private SignificanceModel getSignificanceModelFromQueryLanguage(Query query) throws IllegalArgumentException {
Language explicitLanguage = query.getModel().getLanguage();
Language implicitLanguage = query.getModel().getParsingLanguage();
if (explicitLanguage == null && implicitLanguage == null) {
throw new IllegalArgumentException("No language found in query");
}
if (explicitLanguage != null) {
if (explicitLanguage == Language.UNKNOWN) {
return handleFallBackToUnknownLanguage();
}
var model = significanceModelRegistry.getModel(explicitLanguage);
if (model.isEmpty()) {
throw new IllegalArgumentException("No significance model available for set language " + explicitLanguage);
}
return model.get();
}
if (implicitLanguage == Language.UNKNOWN) {
return handleFallBackToUnknownLanguage();
}
var model = significanceModelRegistry.getModel(implicitLanguage);
if (model.isEmpty()) {
throw new IllegalArgumentException("No significance model available for implicit language " + implicitLanguage);
}
return model.get();
}
private SignificanceModel handleFallBackToUnknownLanguage() throws IllegalArgumentException {
var unknownModel = significanceModelRegistry.getModel(Language.UNKNOWN);
var englishModel = significanceModelRegistry.getModel(Language.ENGLISH);
if (unknownModel.isEmpty() && englishModel.isEmpty()) {
throw new IllegalArgumentException("No significance model available for unknown or english language");
}
return unknownModel.orElseGet(englishModel::get);
}
private void setIDF(Item root, SignificanceModel significanceModel) {
if (root == null || root instanceof NullItem) return;
if (root instanceof WordItem wi) {
var word = wi.getWord();
var documentFrequency = significanceModel.documentFrequency(word);
long N = documentFrequency.corpusSize();
long nq_i = documentFrequency.frequency();
double idf = calculateIDF(N, nq_i);
log.log(Level.FINE, () -> "Setting IDF for " + word + " to " + idf);
wi.setSignificance(idf);
} else if (root instanceof CompositeItem ci) {
for (int i = 0; i < ci.getItemCount(); i++) {
setIDF(ci.getItem(i), significanceModel);
}
}
}
public static double calculateIDF(long N, long nq_i) {
return Math.log(1 + (N - nq_i + 0.5) / (nq_i + 0.5));
}
}
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