Class CombinedFieldQuery
- java.lang.Object
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- org.apache.lucene.search.Query
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- org.apache.lucene.sandbox.search.CombinedFieldQuery
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- All Implemented Interfaces:
Accountable
public final class CombinedFieldQuery extends Query implements Accountable
AQuery
that treats multiple fields as a single stream and scores terms as if you had indexed them as a single term in a single field.The query works as follows:
- Given a list of fields and weights, it pretends there is a synthetic combined field where all terms have been indexed. It computes new term and collection statistics for this combined field.
- It uses a disjunction iterator and
IndexSearcher.getSimilarity()
to score documents.
In order for a similarity to be compatible,
Similarity.computeNorm(org.apache.lucene.index.FieldInvertState)
must be additive: the norm of the combined field is the sum of norms for each individual field. The norms must also be encoded usingSmallFloat.intToByte4(int)
. These requirements hold for all similarities that compute norms the same way asSimilarityBase.computeNorm(org.apache.lucene.index.FieldInvertState)
, which includesBM25Similarity
andDFRSimilarity
. Per-field similarities are not supported.The query also requires that either all fields or no fields have norms enabled. Having only some fields with norms enabled can result in errors.
The scoring is based on BM25F's simple formula described in: http://www.staff.city.ac.uk/~sb317/papers/foundations_bm25_review.pdf. This query implements the same approach but allows other similarities besides
BM25Similarity
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
CombinedFieldQuery.Builder
A builder forCombinedFieldQuery
.private static class
CombinedFieldQuery.CombinedFieldScorer
(package private) class
CombinedFieldQuery.CombinedFieldWeight
(package private) static class
CombinedFieldQuery.FieldAndWeight
private static class
CombinedFieldQuery.WeightedDisiWrapper
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Field Summary
Fields Modifier and Type Field Description private static long
BASE_RAM_BYTES
private java.util.TreeMap<java.lang.String,CombinedFieldQuery.FieldAndWeight>
fieldAndWeights
private Term[]
fieldTerms
private long
ramBytesUsed
private BytesRef[]
terms
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Fields inherited from interface org.apache.lucene.util.Accountable
NULL_ACCOUNTABLE
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Constructor Summary
Constructors Modifier Constructor Description private
CombinedFieldQuery(java.util.TreeMap<java.lang.String,CombinedFieldQuery.FieldAndWeight> fieldAndWeights, BytesRef[] terms)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description Weight
createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost)
Expert: Constructs an appropriate Weight implementation for this query.boolean
equals(java.lang.Object o)
Override and implement query instance equivalence properly in a subclass.java.util.List<Term>
getTerms()
int
hashCode()
Override and implement query hash code properly in a subclass.long
ramBytesUsed()
Return the memory usage of this object in bytes.Query
rewrite(IndexReader reader)
Expert: called to re-write queries into primitive queries.private BooleanQuery
rewriteToBoolean()
java.lang.String
toString(java.lang.String field)
Prints a query to a string, withfield
assumed to be the default field and omitted.private void
validateConsistentNorms(IndexReader reader)
void
visit(QueryVisitor visitor)
Recurse through the query tree, visiting any child queries-
Methods inherited from class org.apache.lucene.search.Query
classHash, sameClassAs, toString
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Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
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Methods inherited from interface org.apache.lucene.util.Accountable
getChildResources
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Field Detail
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BASE_RAM_BYTES
private static final long BASE_RAM_BYTES
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fieldAndWeights
private final java.util.TreeMap<java.lang.String,CombinedFieldQuery.FieldAndWeight> fieldAndWeights
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terms
private final BytesRef[] terms
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fieldTerms
private final Term[] fieldTerms
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ramBytesUsed
private final long ramBytesUsed
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Constructor Detail
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CombinedFieldQuery
private CombinedFieldQuery(java.util.TreeMap<java.lang.String,CombinedFieldQuery.FieldAndWeight> fieldAndWeights, BytesRef[] terms)
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Method Detail
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getTerms
public java.util.List<Term> getTerms()
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toString
public java.lang.String toString(java.lang.String field)
Description copied from class:Query
Prints a query to a string, withfield
assumed to be the default field and omitted.
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equals
public boolean equals(java.lang.Object o)
Description copied from class:Query
Override and implement query instance equivalence properly in a subclass. This is required so thatQueryCache
works properly.Typically a query will be equal to another only if it's an instance of the same class and its document-filtering properties are identical that other instance. Utility methods are provided for certain repetitive code.
- Specified by:
equals
in classQuery
- See Also:
Query.sameClassAs(Object)
,Query.classHash()
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hashCode
public int hashCode()
Description copied from class:Query
Override and implement query hash code properly in a subclass. This is required so thatQueryCache
works properly.- Specified by:
hashCode
in classQuery
- See Also:
Query.equals(Object)
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ramBytesUsed
public long ramBytesUsed()
Description copied from interface:Accountable
Return the memory usage of this object in bytes. Negative values are illegal.- Specified by:
ramBytesUsed
in interfaceAccountable
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rewrite
public Query rewrite(IndexReader reader) throws java.io.IOException
Description copied from class:Query
Expert: called to re-write queries into primitive queries. For example, a PrefixQuery will be rewritten into a BooleanQuery that consists of TermQuerys.Callers are expected to call
rewrite
multiple times if necessary, until the rewritten query is the same as the original query.- Overrides:
rewrite
in classQuery
- Throws:
java.io.IOException
- See Also:
IndexSearcher.rewrite(Query)
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visit
public void visit(QueryVisitor visitor)
Description copied from class:Query
Recurse through the query tree, visiting any child queries
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rewriteToBoolean
private BooleanQuery rewriteToBoolean()
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createWeight
public Weight createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost) throws java.io.IOException
Description copied from class:Query
Expert: Constructs an appropriate Weight implementation for this query.Only implemented by primitive queries, which re-write to themselves.
- Overrides:
createWeight
in classQuery
scoreMode
- How the produced scorers will be consumed.boost
- The boost that is propagated by the parent queries.- Throws:
java.io.IOException
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validateConsistentNorms
private void validateConsistentNorms(IndexReader reader)
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