Package org.apache.lucene.monitor

Class MultipassTermFilteredPresearcher

java.lang.Object

org.apache.lucene.monitor.Presearcher

org.apache.lucene.monitor.TermFilteredPresearcher

org.apache.lucene.monitor.MultipassTermFilteredPresearcher

public class MultipassTermFilteredPresearcher
extends TermFilteredPresearcher

A TermFilteredPresearcher that indexes queries multiple times, with terms collected from different routes through a querytree. Each route will produce a set of terms that are *sufficient* to select the query, and are indexed into a separate, suffixed field.

Incoming documents are then converted to a set of Disjunction queries over each suffixed field, and these queries are combined into a conjunction query, such that the document's set of terms must match a term from each route.

This allows filtering out of documents that contain one half of a two-term phrase query, for example. The query "hello world" will be indexed twice, once under 'hello' and once under 'world'. A document containing the terms "hello there" would match the first field, but not the second, and so would not be selected for matching.

The number of passes the presearcher makes is configurable. More passes will improve the selected/matched ratio, but will take longer to index and will use more RAM.

A minimum weight can we set for terms to be chosen for the second and subsequent passes. This allows users to avoid indexing stopwords, for example.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.monitor.TermFilteredPresearcher

TermFilteredPresearcher.BytesRefHashIterator, TermFilteredPresearcher.DocumentQueryBuilder

Field Summary

Fields inherited from class org.apache.lucene.monitor.TermFilteredPresearcher

DEFAULT_WEIGHTOR

Fields inherited from class org.apache.lucene.monitor.Presearcher

NO_FILTERING

Constructor Summary

Constructors

Constructor	Description
MultipassTermFilteredPresearcher(int passes)	Construct a new MultipassTermFilteredPresearcher using TermFilteredPresearcher.DEFAULT_WEIGHTOR
MultipassTermFilteredPresearcher(int passes, float minWeight, TermWeightor weightor, List<CustomQueryHandler> queryHandlers, Set<String> filterFields)	Construct a new MultipassTermFilteredPresearcher

Method Summary

Modifier and Type	Method	Description
Document	buildQueryDocument(QueryTree querytree)	Builds a Document from the terms extracted from a query
protected TermFilteredPresearcher.DocumentQueryBuilder	getQueryBuilder()	Returns a TermFilteredPresearcher.DocumentQueryBuilder for this presearcher

Methods inherited from class org.apache.lucene.monitor.TermFilteredPresearcher

buildQuery, collectTerms, indexQuery

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MultipassTermFilteredPresearcher

public MultipassTermFilteredPresearcher(int passes,
                                        float minWeight,
                                        TermWeightor weightor,
                                        List<CustomQueryHandler> queryHandlers,
                                        Set<String> filterFields)

Construct a new MultipassTermFilteredPresearcher

Parameters:

passes - the number of times a query should be indexed

minWeight - the minimum weight a querytree should be advanced over

weightor - the TreeWeightor to use

queryHandlers - a list of custom query handlers

filterFields - a set of fields to use as filters

MultipassTermFilteredPresearcher

public MultipassTermFilteredPresearcher(int passes)

Construct a new MultipassTermFilteredPresearcher using TermFilteredPresearcher.DEFAULT_WEIGHTOR

Note that this will be constructed with a minimum advance weight of zero

Parameters:

passes - the number of times a query should be indexed

Method Detail

getQueryBuilder

protected TermFilteredPresearcher.DocumentQueryBuilder getQueryBuilder()

Description copied from class: TermFilteredPresearcher

Returns a TermFilteredPresearcher.DocumentQueryBuilder for this presearcher

Overrides:

getQueryBuilder in class TermFilteredPresearcher

buildQueryDocument

public Document buildQueryDocument(QueryTree querytree)

Description copied from class: TermFilteredPresearcher

Builds a Document from the terms extracted from a query

Overrides:

buildQueryDocument in class TermFilteredPresearcher