org.apache.lucene.search.grouping.term
Class TermFirstPassGroupingCollector

java.lang.Object
  extended by org.apache.lucene.search.Collector
      extended by org.apache.lucene.search.grouping.AbstractFirstPassGroupingCollector<BytesRef>
          extended by org.apache.lucene.search.grouping.term.TermFirstPassGroupingCollector

public class TermFirstPassGroupingCollector
extends AbstractFirstPassGroupingCollector<BytesRef>

Concrete implementation of AbstractFirstPassGroupingCollector that groups based on field values and more specifically uses SortedDocValues to collect groups.

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

Field Summary
 
Fields inherited from class org.apache.lucene.search.grouping.AbstractFirstPassGroupingCollector
orderedGroups
 
Constructor Summary
TermFirstPassGroupingCollector(String groupField, Sort groupSort, int topNGroups)
          Create the first pass collector.
 
Method Summary
protected  BytesRef copyDocGroupValue(BytesRef groupValue, BytesRef reuse)
          Returns a copy of the specified group value by creating a new instance and copying the value from the specified groupValue in the new instance.
protected  BytesRef getDocGroupValue(int doc)
          Returns the group value for the specified doc.
 void setNextReader(AtomicReaderContext readerContext)
           
 
Methods inherited from class org.apache.lucene.search.grouping.AbstractFirstPassGroupingCollector
acceptsDocsOutOfOrder, collect, getTopGroups, setScorer
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

TermFirstPassGroupingCollector

public TermFirstPassGroupingCollector(String groupField,
                                      Sort groupSort,
                                      int topNGroups)
                               throws IOException
Create the first pass collector.

Parameters:
groupField - The field used to group documents. This field must be single-valued and indexed (FieldCache is used to access its value per-document).
groupSort - The Sort 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.
Throws:
IOException - When I/O related errors occur
Method Detail

getDocGroupValue

protected BytesRef getDocGroupValue(int doc)
Description copied from class: AbstractFirstPassGroupingCollector
Returns the group value for the specified doc.

Specified by:
getDocGroupValue in class AbstractFirstPassGroupingCollector<BytesRef>
Parameters:
doc - The specified doc
Returns:
the group value for the specified doc

copyDocGroupValue

protected BytesRef copyDocGroupValue(BytesRef groupValue,
                                     BytesRef reuse)
Description copied from class: AbstractFirstPassGroupingCollector
Returns a copy of the specified group value by creating a new instance and copying the value from the specified groupValue in the new instance. Or optionally the reuse argument can be used to copy the group value in.

Specified by:
copyDocGroupValue in class AbstractFirstPassGroupingCollector<BytesRef>
Parameters:
groupValue - The group value to copy
reuse - Optionally a reuse instance to prevent a new instance creation
Returns:
a copy of the specified group value

setNextReader

public void setNextReader(AtomicReaderContext readerContext)
                   throws IOException
Overrides:
setNextReader in class AbstractFirstPassGroupingCollector<BytesRef>
Throws:
IOException


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