Class JoinUtil

Utility for query time joining using Lucene.Net.Join.TermsQuery and Lucene.Net.Join.TermsCollector.

This is a Lucene.NET EXPERIMENTAL API, use at your own risk

Inheritance

System.Object

JoinUtil

Namespace: Lucene.Net.Join

Assembly: Lucene.Net.Join.dll

Syntax

public sealed class JoinUtil : object

Methods

CreateJoinQuery(String, Boolean, String, Query, IndexSearcher, ScoreMode)

Method for query time joining.

Execute the returned query with a to retrieve all documents that have the same terms in the to field that match with documents matching the specified fromQuery and have the same terms in the from field.

In the case a single document relates to more than one document the multipleValuesPerDocument option should be set to true. When the multipleValuesPerDocument is set to true only the the score from the first encountered join value originating from the 'from' side is mapped into the 'to' side. Even in the case when a second join value related to a specific document yields a higher score. Obviously this doesn't apply in the case that None is used, since no scores are computed at all.

Memory considerations: During joining all unique join values are kept in memory. On top of that when the scoreMode isn't set to None a float value per unique join value is kept in memory for computing scores. When scoreMode is set to Avg also an additional integer value is kept in memory per unique join value.

Declaration

public static Query CreateJoinQuery(string fromField, bool multipleValuesPerDocument, string toField, Query fromQuery, IndexSearcher fromSearcher, ScoreMode scoreMode)

Parameters

Type	Name	Description
System.String	fromField	The from field to join from
System.Boolean	multipleValuesPerDocument	Whether the from field has multiple terms per document
System.String	toField	The to field to join to
Query	fromQuery	The query to match documents on the from side
IndexSearcher	fromSearcher	The searcher that executed the specified fromQuery
ScoreMode	scoreMode	Instructs how scores from the fromQuery are mapped to the returned query

Returns

Type	Description
Query	A instance that can be used to join documents based on the terms in the from and to field