Module org.apache.lucene.grouping
Class AllGroupHeadsCollector<T>
java.lang.Object
org.apache.lucene.search.SimpleCollector
org.apache.lucene.search.grouping.AllGroupHeadsCollector<T>
- All Implemented Interfaces:
Collector
,LeafCollector
- Direct Known Subclasses:
AllGroupHeadsCollector.ScoringGroupHeadsCollector
,AllGroupHeadsCollector.SortingGroupHeadsCollector
This collector specializes in collecting the most relevant document (group head) for each group
that matches the query.
Clients should create new collectors by calling newCollector(GroupSelector, Sort)
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic class
Represents a group head.private static class
private static class
Specialized implementation for sorting by scoreprivate static class
private static class
General implementation using aFieldComparator
to select the group head -
Field Summary
FieldsModifier and TypeFieldDescriptionprotected final int
protected LeafReaderContext
private final GroupSelector<T>
protected Map<T,
AllGroupHeadsCollector.GroupHead<T>> protected final int[]
protected Scorable
protected final Sort
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Constructor Summary
ConstructorsModifierConstructorDescriptionprivate
AllGroupHeadsCollector
(GroupSelector<T> selector, Sort sort) -
Method Summary
Modifier and TypeMethodDescriptionvoid
collect
(int doc) Called once for every document matching a query, with the unbased document number.protected void
doSetNextReader
(LeafReaderContext context) This method is called before collectingcontext
.protected Collection<? extends AllGroupHeadsCollector.GroupHead<T>>
Returns the collected group heads.int
static <T> AllGroupHeadsCollector<T>
newCollector
(GroupSelector<T> selector, Sort sort) Create a new AllGroupHeadsCollector based on the type of within-group Sort requiredprotected abstract AllGroupHeadsCollector.GroupHead<T>
newGroupHead
(int doc, T value, LeafReaderContext context, Scorable scorer) Create a new GroupHead for the given group value, initialized with a doc, context and scorerint[]
retrieveGroupHeads
(int maxDoc) Indicates what features are required from the scorer.void
Called before successive calls toLeafCollector.collect(int)
.Methods inherited from class org.apache.lucene.search.SimpleCollector
getLeafCollector
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.LeafCollector
collect, competitiveIterator, finish
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Field Details
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groupSelector
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sort
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reversed
protected final int[] reversed -
compIDXEnd
protected final int compIDXEnd -
heads
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context
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scorer
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Constructor Details
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AllGroupHeadsCollector
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Method Details
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newCollector
Create a new AllGroupHeadsCollector based on the type of within-group Sort required- Type Parameters:
T
- the group value type- Parameters:
selector
- a GroupSelector to define the groupssort
- the within-group sort to use to choose the group head document
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retrieveGroupHeads
- Parameters:
maxDoc
- The maxDoc of the top levelIndexReader
.- Returns:
- a
FixedBitSet
containing all group heads.
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retrieveGroupHeads
public int[] retrieveGroupHeads()- Returns:
- an int array containing all group heads. The size of the array is equal to number of collected unique groups.
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groupHeadsSize
public int groupHeadsSize()- Returns:
- the number of group heads found for a query.
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getCollectedGroupHeads
Returns the collected group heads. Subsequent calls should return the same group heads.- Returns:
- the collected group heads
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collect
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
StoredFields.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:
IOException
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scoreMode
Description copied from interface:Collector
Indicates what features are required from the scorer. -
doSetNextReader
Description copied from class:SimpleCollector
This method is called before collectingcontext
.- Overrides:
doSetNextReader
in classSimpleCollector
- Throws:
IOException
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setScorer
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:
IOException
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newGroupHead
protected abstract AllGroupHeadsCollector.GroupHead<T> newGroupHead(int doc, T value, LeafReaderContext context, Scorable scorer) throws IOException Create a new GroupHead for the given group value, initialized with a doc, context and scorer- Throws:
IOException
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