Class FieldMaskingSpanQuery
SpanQuery
objects participate in composite single-field SpanQueries by
'lying' about their search field. That is, the masked SpanQuery will function as normal, but
SpanQuery.getField()
simply hands back the value supplied in this class's constructor.
This can be used to support Queries like SpanNearQuery
or SpanOrQuery
across
different fields, which is not ordinarily permitted.
This can be useful for denormalized relational data: for example, when indexing a document with conceptually many 'children':
teacherid: 1 studentfirstname: james studentsurname: jones teacherid: 2 studenfirstname: james studentsurname: smith studentfirstname: sally studentsurname: jones
a SpanNearQuery with a slop of 0 can be applied across two SpanTermQuery
objects as
follows:
SpanQuery q1 = new SpanTermQuery(new Term("studentfirstname", "james")); SpanQuery q2 = new SpanTermQuery(new Term("studentsurname", "jones")); SpanQuery q2m = new FieldMaskingSpanQuery(q2, "studentfirstname"); Query q = new SpanNearQuery(new SpanQuery[]{q1, q2m}, -1, false);to search for 'studentfirstname:james studentsurname:jones' and find teacherid 1 without matching teacherid 2 (which has a 'james' in position 0 and 'jones' in position 1).
Note: as getField()
returns the masked field, scoring will be done using the
Similarity and collection statistics of the field name supplied, but with the term statistics of
the real field. This may lead to exceptions, poor performance, and unexpected scoring behaviour.
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Field Summary
Fields -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptioncreateWeight
(IndexSearcher searcher, ScoreMode scoreMode, float boost) Expert: Constructs an appropriate Weight implementation for this query.boolean
Override and implement query instance equivalence properly in a subclass.private boolean
equalsTo
(FieldMaskingSpanQuery other) getField()
Returns the name of the field matched by this query.int
hashCode()
Override and implement query hash code properly in a subclass.rewrite
(IndexReader reader) Expert: called to re-write queries into primitive queries.Prints a query to a string, withfield
assumed to be the default field and omitted.void
visit
(QueryVisitor visitor) Recurse through the query tree, visiting any child queriesMethods inherited from class org.apache.lucene.queries.spans.SpanQuery
getTermStates, getTermStates
Methods inherited from class org.apache.lucene.search.Query
classHash, sameClassAs, toString
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Field Details
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maskedQuery
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field
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Constructor Details
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FieldMaskingSpanQuery
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Method Details
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getField
Description copied from class:SpanQuery
Returns the name of the field matched by this query. -
getMaskedQuery
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createWeight
public SpanWeight createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost) throws 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.
- Specified by:
createWeight
in classSpanQuery
scoreMode
- How the produced scorers will be consumed.boost
- The boost that is propagated by the parent queries.- Throws:
IOException
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rewrite
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:
IOException
- See Also:
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visit
Description copied from class:Query
Recurse through the query tree, visiting any child queries -
toString
Description copied from class:Query
Prints a query to a string, withfield
assumed to be the default field and omitted. -
equals
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.
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equalsTo
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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.
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