org.apache.lucene.search.suggest.document

Class NRTSuggester

java.lang.Object

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

public final class NRTSuggester
extends java.lang.Object

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

Method Summary

Modifier and Type	Method and Description
java.util.Collection<Accountable>	getChildResources()
static NRTSuggester	load(IndexInput input, CompletionPostingsFormat.FSTLoadMode fstLoadMode) Loads a NRTSuggester from org.apache.lucene.store.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 Detail

ramBytesUsed

public long ramBytesUsed()

getChildResources

public java.util.Collection<Accountable> getChildResources()

lookup

public void lookup(CompletionScorer scorer,
                   Bits acceptDocs,
                   TopSuggestDocsCollector collector)
            throws java.io.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:

java.io.IOException

load

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

Loads a NRTSuggester from org.apache.lucene.store.IndexInput on or off-heap depending on the provided fstLoadMode

Throws:

java.io.IOException