Class BlockGroupingCollector
- java.lang.Object
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- org.apache.lucene.search.SimpleCollector
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- org.apache.lucene.search.grouping.BlockGroupingCollector
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- All Implemented Interfaces:
Collector
,LeafCollector
public class BlockGroupingCollector extends SimpleCollector
BlockGroupingCollector performs grouping with a single pass collector, as long as you are grouping by a doc block field, ie all documents sharing a given group value were indexed as a doc block using the atomicIndexWriter.addDocuments()
orIndexWriter.updateDocuments()
API.This results in faster performance (~25% faster QPS) than the two-pass grouping collectors, with the tradeoff being that the documents in each group must always be indexed as a block. This collector also fills in TopGroups.totalGroupCount without requiring the separate
AllGroupsCollector
. However, this collector does not fill in the groupValue of each group; this field will always be null.NOTE: this collector makes no effort to verify the docs were in fact indexed as a block, so it's up to you to ensure this was the case.
See
org.apache.lucene.search.grouping
for more details including a full code example.
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Nested Class Summary
Nested Classes Modifier and Type Class Description private class
BlockGroupingCollector.GroupQueue
private static class
BlockGroupingCollector.OneGroup
private static class
BlockGroupingCollector.ScoreAndDoc
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Field Summary
Fields Modifier and Type Field Description private int
bottomSlot
private FieldComparator<?>[]
comparators
private int
compIDXEnd
private LeafReaderContext
currentReaderContext
private int
docBase
private boolean
groupCompetes
private int
groupEndDocID
private BlockGroupingCollector.GroupQueue
groupQueue
private Sort
groupSort
private Weight
lastDocPerGroup
private DocIdSetIterator
lastDocPerGroupBits
private LeafFieldComparator[]
leafComparators
private boolean
needsScores
private int[]
pendingSubDocs
private float[]
pendingSubScores
private boolean
queueFull
private int[]
reversed
private Scorable
scorer
private int
subDocUpto
private int
topGroupDoc
private int
topNGroups
private int
totalGroupCount
private int
totalHitCount
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Constructor Summary
Constructors Constructor Description BlockGroupingCollector(Sort groupSort, int topNGroups, boolean needsScores, Weight lastDocPerGroup)
Create the single pass collector.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
collect(int doc)
Called once for every document matching a query, with the unbased document number.protected void
doSetNextReader(LeafReaderContext readerContext)
This method is called before collectingcontext
.TopGroups<?>
getTopGroups(Sort withinGroupSort, int groupOffset, int withinGroupOffset, int maxDocsPerGroup)
Returns the grouped results.private void
processGroup()
ScoreMode
scoreMode()
Indicates what features are required from the scorer.void
setScorer(Scorable scorer)
Called before successive calls toLeafCollector.collect(int)
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Methods inherited from class org.apache.lucene.search.SimpleCollector
getLeafCollector
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Field Detail
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pendingSubDocs
private int[] pendingSubDocs
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pendingSubScores
private float[] pendingSubScores
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subDocUpto
private int subDocUpto
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groupSort
private final Sort groupSort
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topNGroups
private final int topNGroups
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lastDocPerGroup
private final Weight lastDocPerGroup
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needsScores
private final boolean needsScores
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comparators
private final FieldComparator<?>[] comparators
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leafComparators
private final LeafFieldComparator[] leafComparators
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reversed
private final int[] reversed
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compIDXEnd
private final int compIDXEnd
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bottomSlot
private int bottomSlot
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queueFull
private boolean queueFull
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currentReaderContext
private LeafReaderContext currentReaderContext
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topGroupDoc
private int topGroupDoc
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totalHitCount
private int totalHitCount
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totalGroupCount
private int totalGroupCount
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docBase
private int docBase
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groupEndDocID
private int groupEndDocID
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lastDocPerGroupBits
private DocIdSetIterator lastDocPerGroupBits
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scorer
private Scorable scorer
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groupQueue
private final BlockGroupingCollector.GroupQueue groupQueue
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groupCompetes
private boolean groupCompetes
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Constructor Detail
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BlockGroupingCollector
public BlockGroupingCollector(Sort groupSort, int topNGroups, boolean needsScores, Weight lastDocPerGroup)
Create the single pass collector.- Parameters:
groupSort
- TheSort
used to sort the groups. The top sorted document within each group according to groupSort, determines how that group sorts against other groups. This must be non-null, ie, if you want to groupSort by relevance use Sort.RELEVANCE.topNGroups
- How many top groups to keep.needsScores
- true if the collected documents require scores, either because relevance is included in the withinGroupSort or because you plan to pass true for either getSscores or getMaxScores togetTopGroups(org.apache.lucene.search.Sort, int, int, int)
lastDocPerGroup
- aWeight
that marks the last document in each group.
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Method Detail
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processGroup
private void processGroup() throws java.io.IOException
- Throws:
java.io.IOException
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getTopGroups
public TopGroups<?> getTopGroups(Sort withinGroupSort, int groupOffset, int withinGroupOffset, int maxDocsPerGroup) throws java.io.IOException
Returns the grouped results. Returns null if the number of groups collected is <= groupOffset.NOTE: This collector is unable to compute the groupValue per group so it will always be null. This is normally not a problem, as you can obtain the value just like you obtain other values for each matching document (eg, via stored fields, via DocValues, etc.)
- Parameters:
withinGroupSort
- TheSort
used to sort documents within each group.groupOffset
- Which group to start fromwithinGroupOffset
- Which document to start from within each groupmaxDocsPerGroup
- How many top documents to keep within each group.- Throws:
java.io.IOException
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setScorer
public void setScorer(Scorable scorer) throws java.io.IOException
Description copied from interface:LeafCollector
Called before successive calls toLeafCollector.collect(int)
. Implementations that need the score of the current document (passed-in toLeafCollector.collect(int)
), should save the passed-in Scorer and call scorer.score() when needed.- Specified by:
setScorer
in interfaceLeafCollector
- Overrides:
setScorer
in classSimpleCollector
- Throws:
java.io.IOException
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collect
public void collect(int doc) throws java.io.IOException
Description copied from interface:LeafCollector
Called once for every document matching a query, with the unbased document number.Note: The collection of the current segment can be terminated by throwing a
CollectionTerminatedException
. In this case, the last docs of the currentLeafReaderContext
will be skipped andIndexSearcher
will swallow the exception and continue collection with the next leaf.Note: This is called in an inner search loop. For good search performance, implementations of this method should not call
IndexSearcher.doc(int)
orIndexReader.document(int)
on every hit. Doing so can slow searches by an order of magnitude or more.- Specified by:
collect
in interfaceLeafCollector
- Specified by:
collect
in classSimpleCollector
- Throws:
java.io.IOException
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doSetNextReader
protected void doSetNextReader(LeafReaderContext readerContext) throws java.io.IOException
Description copied from class:SimpleCollector
This method is called before collectingcontext
.- Overrides:
doSetNextReader
in classSimpleCollector
- Throws:
java.io.IOException
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