Package org.apache.lucene.search.suggest.document

Class NRTSuggester

java.lang.Object

org.apache.lucene.search.suggest.document.NRTSuggester

All Implemented Interfaces:

Accountable

public final class NRTSuggester
extends Object
implements Accountable

NRTSuggester executes Top N search on a weighted FST specified by a CompletionScorer

See lookup(CompletionScorer, Bits, TopSuggestDocsCollector) for more implementation details.

FST Format:

• Input: analyzed forms of input terms
• Output: Pair<Long, BytesRef> containing weight, surface form and docID

NOTE:

• having too many deletions or using a very restrictive filter can make the search inadmissible due to over-pruning of potential paths. See CompletionScorer.accept(int, Bits)
• when matched documents are arbitrarily filtered (CompletionScorer.filtered set to true, it is assumed that the filter will roughly filter out half the number of documents that match the provided automaton
• lookup performance will degrade as more accepted completions lead to filtered out documents

WARNING: This API is experimental and might change in incompatible ways in the next release.

Field Summary

Fields inherited from interface org.apache.lucene.util.Accountable

NULL_ACCOUNTABLE

Method Summary

Modifier and Type	Method	Description
Collection<Accountable>	getChildResources()
static NRTSuggester	load(IndexInput input, CompletionPostingsFormat.FSTLoadMode fstLoadMode)	Loads a NRTSuggester from IndexInput on or off-heap depending on the provided fstLoadMode
void	lookup(CompletionScorer scorer, Bits acceptDocs, TopSuggestDocsCollector collector)	Collects at most TopSuggestDocsCollector.getCountToCollect() completions that match the provided CompletionScorer.
long	ramBytesUsed()

Methods inherited from class java.lang.Object

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

Method Details

ramBytesUsed

public long ramBytesUsed()

Specified by:

ramBytesUsed in interface Accountable

getChildResources

public Collection<Accountable> getChildResources()

Specified by:

getChildResources in interface Accountable

lookup

public void lookup(CompletionScorer scorer,
 Bits acceptDocs,
 TopSuggestDocsCollector collector)
            throws IOException

Collects at most TopSuggestDocsCollector.getCountToCollect() completions that match the provided CompletionScorer.

The CompletionScorer.automaton is intersected with the fst. CompletionScorer.weight is used to compute boosts and/or extract context for each matched partial paths. A top N search is executed on fst seeded with the matched partial paths. Upon reaching a completed path, CompletionScorer.accept(int, Bits) and CompletionScorer.score(float, float) is used on the document id, index weight and query boost to filter and score the entry, before being collected via TopSuggestDocsCollector.collect(int, CharSequence, CharSequence, float)

Throws:

IOException

load

public static NRTSuggester load(IndexInput input,
 CompletionPostingsFormat.FSTLoadMode fstLoadMode)
                         throws IOException

Loads a NRTSuggester from IndexInput on or off-heap depending on the provided fstLoadMode

Throws:

IOException