Class Weight
- All Implemented Interfaces:
SegmentCacheable
- Direct Known Subclasses:
ConstantScoreWeight
,DisjunctionMaxQuery.DisjunctionMaxWeight
,FilterWeight
,IndriAndWeight
,PhraseWeight
The purpose of Weight
is to ensure searching does not modify a Query
, so that
a Query
instance can be reused.
IndexSearcher
dependent state of the query should reside in the Weight
.
LeafReader
dependent state should reside in the Scorer
.
Since Weight
creates Scorer
instances for a given LeafReaderContext
(scorer(org.apache.lucene.index.LeafReaderContext)
) callers must maintain the relationship
between the searcher's top-level IndexReaderContext
and the context used to create a
Scorer
.
A Weight
is used in the following way:
- A
Weight
is constructed by a top-level query, given aIndexSearcher
(Query.createWeight(IndexSearcher, ScoreMode, float)
). - A
Scorer
is constructed byscorer(org.apache.lucene.index.LeafReaderContext)
.
- Since:
- 2.9
-
Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionprotected static class
Just wraps a Scorer and performs top scoring using it.protected static final class
A wrap for default scorer supplier. -
Field Summary
Fields -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionfinal BulkScorer
bulkScorer
(LeafReaderContext context) Helper method that delegates toscorerSupplier(LeafReaderContext)
.int
count
(LeafReaderContext context) Counts the number of live documents that match a givenparentQuery
in a leaf.abstract Explanation
explain
(LeafReaderContext context, int doc) An explanation of the score computation for the named document.final Query
getQuery()
The query that this concerns.matches
(LeafReaderContext context, int doc) ReturnsMatches
for a specific document, ornull
if the document does not match the parent queryfinal Scorer
scorer
(LeafReaderContext context) Optional method that delegates to scorerSupplier.abstract ScorerSupplier
scorerSupplier
(LeafReaderContext context) Get aScorerSupplier
, which allows knowing the cost of theScorer
before building it.Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface org.apache.lucene.search.SegmentCacheable
isCacheable
-
Field Details
-
parentQuery
-
-
Constructor Details
-
Weight
Sole constructor, typically invoked by sub-classes.- Parameters:
query
- the parent query
-
-
Method Details
-
matches
ReturnsMatches
for a specific document, ornull
if the document does not match the parent queryA query match that contains no position information (for example, a Point or DocValues query) will return
MatchesUtils.MATCH_WITH_NO_TERMS
- Parameters:
context
- the reader's context to create theMatches
fordoc
- the document's id relative to the given context's reader- Throws:
IOException
- WARNING: This API is experimental and might change in incompatible ways in the next release.
-
explain
An explanation of the score computation for the named document.- Parameters:
context
- the readers context to create theExplanation
for.doc
- the document's id relative to the given context's reader- Returns:
- an Explanation for the score
- Throws:
IOException
- if anIOException
occurs
-
getQuery
The query that this concerns. -
scorer
Optional method that delegates to scorerSupplier.Returns a
Scorer
which can iterate in order over all matching documents and assign them a score. A scorer for the sameLeafReaderContext
instance may be requested multiple times as part of a single search call.NOTE: null can be returned if no documents will be scored by this query.
NOTE: The returned
Scorer
does not haveLeafReader.getLiveDocs()
applied, they need to be checked on top.- Parameters:
context
- theLeafReaderContext
for which to return theScorer
.- Returns:
- a
Scorer
which scores documents in/out-of order. - Throws:
IOException
- if there is a low-level I/O error
-
scorerSupplier
Get aScorerSupplier
, which allows knowing the cost of theScorer
before building it. A scorer supplier for the sameLeafReaderContext
instance may be requested multiple times as part of a single search call.Note: It must return null if the scorer is null.
- Parameters:
context
- the leaf reader context- Returns:
- a
ScorerSupplier
providing the scorer, or null if scorer is null - Throws:
IOException
- if an IOException occurs- See Also:
-
bulkScorer
Helper method that delegates toscorerSupplier(LeafReaderContext)
. It is implemented asScorerSupplier scorerSupplier = scorerSupplier(context); if (scorerSupplier == null) { // No docs match return null; } scorerSupplier.setTopLevelScoringClause(); return scorerSupplier.bulkScorer();
A bulk scorer for the sameLeafReaderContext
instance may be requested multiple times as part of a single search call.- Throws:
IOException
-
count
Counts the number of live documents that match a givenparentQuery
in a leaf.The default implementation returns -1 for every query. This indicates that the count could not be computed in sub-linear time.
Specific query classes should override it to provide other accurate sub-linear implementations (that actually return the count). Look at
MatchAllDocsQuery.createWeight(IndexSearcher, ScoreMode, float)
for an exampleWe use this property of the function to count hits in
IndexSearcher.count(Query)
.- Parameters:
context
- theLeafReaderContext
for which to return the count.- Returns:
- integer count of the number of matches
- Throws:
IOException
- if there is a low-level I/O error
-