Class FilteredQuery

A query that applies a filter to the results of another query.

Note: the bits are retrieved from the filter each time this query is used in a search - use a CachingWrapperFilter to avoid regenerating the bits every time.

@since 1.4

Inheritance

System.Object

Query

FilteredQuery

Inherited Members

Query.Boost

Query.ToString()

Query.Clone()

Namespace: Lucene.Net.Search

Assembly: Lucene.Net.dll

Syntax

public class FilteredQuery : Query

Constructors

FilteredQuery(Query, Filter)

Constructs a new query which applies a filter to the results of the original query. GetDocIdSet(AtomicReaderContext, IBits) will be called every time this query is used in a search.

Declaration

public FilteredQuery(Query query, Filter filter)

Parameters

Type	Name	Description
Query	query	Query to be filtered, cannot be null.
Filter	filter	Filter to apply to query results, cannot be null.

FilteredQuery(Query, Filter, FilteredQuery.FilterStrategy)

Expert: Constructs a new query which applies a filter to the results of the original query. GetDocIdSet(AtomicReaderContext, IBits) will be called every time this query is used in a search.

Declaration

public FilteredQuery(Query query, Filter filter, FilteredQuery.FilterStrategy strategy)

Parameters

Type	Name	Description
Query	query	Query to be filtered, cannot be null.
Filter	filter	Filter to apply to query results, cannot be null.
FilteredQuery.FilterStrategy	strategy	A filter strategy used to create a filtered scorer.

See Also

FilteredQuery.FilterStrategy

Fields

LEAP_FROG_FILTER_FIRST_STRATEGY

A filter strategy that uses a "leap-frog" approach (also called "zig-zag join"). The scorer and the filter take turns trying to advance to each other's next matching document, often jumping past the target document. When both land on the same document, it's collected.

Note: this strategy uses the filter to lead the iteration.

Declaration

public static readonly FilteredQuery.FilterStrategy LEAP_FROG_FILTER_FIRST_STRATEGY

Field Value

Type	Description
FilteredQuery.FilterStrategy

LEAP_FROG_QUERY_FIRST_STRATEGY

A filter strategy that uses a "leap-frog" approach (also called "zig-zag join"). The scorer and the filter take turns trying to advance to each other's next matching document, often jumping past the target document. When both land on the same document, it's collected.

Note: this strategy uses the query to lead the iteration.

Declaration

public static readonly FilteredQuery.FilterStrategy LEAP_FROG_QUERY_FIRST_STRATEGY

Field Value

Type	Description
FilteredQuery.FilterStrategy

QUERY_FIRST_FILTER_STRATEGY

A filter strategy that advances the Query or rather its Scorer first and consults the filter DocIdSet for each matched document.

Note: this strategy requires a Bits to return a non-null value. Otherwise this strategy falls back to LEAP_FROG_QUERY_FIRST_STRATEGY

Use this strategy if the filter computation is more expensive than document scoring or if the filter has a linear running time to compute the next matching doc like exact geo distances.

Declaration

public static readonly FilteredQuery.FilterStrategy QUERY_FIRST_FILTER_STRATEGY

Field Value

Type	Description
FilteredQuery.FilterStrategy

RANDOM_ACCESS_FILTER_STRATEGY

A FilteredQuery.FilterStrategy that conditionally uses a random access filter if the given DocIdSet supports random access (returns a non-null value from Bits) and UseRandomAccess(IBits, Int32) returns true. Otherwise this strategy falls back to a "zig-zag join" ( LEAP_FROG_FILTER_FIRST_STRATEGY) strategy.

Note: this strategy is the default strategy in FilteredQuery

Declaration

public static readonly FilteredQuery.FilterStrategy RANDOM_ACCESS_FILTER_STRATEGY

Field Value

Type	Description
FilteredQuery.FilterStrategy

Properties

Filter

Returns this FilteredQuery's filter

Declaration

public Filter Filter { get; }

Property Value

Type	Description
Filter

Query

Returns this FilteredQuery's (unfiltered) Query

Declaration

public Query Query { get; }

Property Value

Type	Description
Query

Strategy

Returns this FilteredQuery's FilteredQuery.FilterStrategy

Declaration

public virtual FilteredQuery.FilterStrategy Strategy { get; }

Property Value

Type	Description
FilteredQuery.FilterStrategy

Methods

CreateWeight(IndexSearcher)

Returns a Weight that applies the filter to the enclosed query's Weight. this is accomplished by overriding the Scorer returned by the Weight.

Declaration

public override Weight CreateWeight(IndexSearcher searcher)

Parameters

Type	Name	Description
IndexSearcher	searcher

Returns

Type	Description
Weight

Overrides

Query.CreateWeight(IndexSearcher)

Equals(Object)

Returns true if o is equal to this.

Declaration

public override bool Equals(object o)

Parameters

Type	Name	Description
System.Object	o

Returns

Type	Description
System.Boolean

Overrides

Query.Equals(Object)

ExtractTerms(ISet<Term>)

Expert: adds all terms occurring in this query to the terms set. Only works if this query is in its rewritten (Rewrite(IndexReader)) form.

Declaration

public override void ExtractTerms(ISet<Term> terms)

Parameters

Type	Name	Description
ISet<Term>	terms

Overrides

Query.ExtractTerms(ISet<Term>)

GetHashCode()

Returns a hash code value for this object.

Declaration

public override int GetHashCode()

Returns

Type	Description
System.Int32

Overrides

Query.GetHashCode()

Rewrite(IndexReader)

Rewrites the query. If the wrapped is an instance of MatchAllDocsQuery it returns a ConstantScoreQuery. Otherwise it returns a new FilteredQuery wrapping the rewritten query.

Declaration

public override Query Rewrite(IndexReader reader)

Parameters

Type	Name	Description
IndexReader	reader

Returns

Type	Description
Query

Overrides

Query.Rewrite(IndexReader)

ToString(String)

Prints a user-readable version of this query.

Declaration

public override string ToString(string s)

Parameters

Type	Name	Description
System.String	s

Returns

Type	Description
System.String

Overrides

Query.ToString(String)

See Also

CachingWrapperFilter