Package org.apache.lucene.search
Class NGramPhraseQuery
java.lang.Object
org.apache.lucene.search.Query
org.apache.lucene.search.NGramPhraseQuery
This is a
PhraseQuery which is optimized for n-gram phrase query. For example, when you
query "ABCD" on a 2-gram field, you may want to use NGramPhraseQuery rather than PhraseQuery, because NGramPhraseQuery will Query.rewrite(IndexSearcher) the query to
"AB/0 CD/2", while PhraseQuery will query "AB/0 BC/1 CD/2" (where term/position).-
Constructor Summary
ConstructorsConstructorDescriptionNGramPhraseQuery(int n, PhraseQuery query) Constructor that takes gram size. -
Method Summary
Modifier and TypeMethodDescriptionbooleanOverride and implement query instance equivalence properly in a subclass.intgetN()Return the n in n-gramint[]Return the list of relative positions that each term should appear at.Term[]getTerms()Return the list of terms.inthashCode()Override and implement query hash code properly in a subclass.rewrite(IndexSearcher indexSearcher) Expert: called to re-write queries into primitive queries.Prints a query to a string, withfieldassumed to be the default field and omitted.voidvisit(QueryVisitor visitor) Recurse through the query tree, visiting any child queries.Methods inherited from class org.apache.lucene.search.Query
classHash, createWeight, sameClassAs, toString
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Constructor Details
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NGramPhraseQuery
Constructor that takes gram size.- Parameters:
n- n-gram size
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Method Details
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rewrite
Description copied from class:QueryExpert: 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
rewritemultiple times if necessary, until the rewritten query is the same as the original query.The rewrite process may be able to make use of IndexSearcher's executor and be executed in parallel if the executor is provided.
- Overrides:
rewritein classQuery- Throws:
IOException- See Also:
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visit
Description copied from class:QueryRecurse through the query tree, visiting any child queries. -
equals
Description copied from class:QueryOverride and implement query instance equivalence properly in a subclass. This is required so thatQueryCacheworks 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 to those of the other instance. Utility methods are provided for certain repetitive code.
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hashCode
public int hashCode()Description copied from class:QueryOverride and implement query hash code properly in a subclass. This is required so thatQueryCacheworks properly. -
getN
public int getN()Return the n in n-gram -
getTerms
Return the list of terms. -
getPositions
public int[] getPositions()Return the list of relative positions that each term should appear at. -
toString
Description copied from class:QueryPrints a query to a string, withfieldassumed to be the default field and omitted.
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