org.apache.lucene.search.grouping
Class TermFirstPassGroupingCollector

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

public class TermFirstPassGroupingCollector
extends AbstractFirstPassGroupingCollector<String>

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

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

Constructor Summary
TermFirstPassGroupingCollector(String groupField, Sort groupSort, int topNGroups)
          Create the first pass collector.
 
Method Summary
protected  String copyDocGroupValue(String groupValue, String 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  String getDocGroupValue(int doc)
          Returns the group value for the specified doc.
 void setNextReader(IndexReader reader, int docBase)
          Called before collecting from each IndexReader.
 
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 String getDocGroupValue(int doc)
Description copied from class: AbstractFirstPassGroupingCollector
Returns the group value for the specified doc.

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

copyDocGroupValue

protected String copyDocGroupValue(String groupValue,
                                   String 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<String>
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(IndexReader reader,
                          int docBase)
                   throws IOException
Description copied from class: Collector
Called before collecting from each IndexReader. All doc ids in Collector.collect(int) will correspond to reader. Add docBase to the current IndexReaders internal document id to re-base ids in Collector.collect(int).

Overrides:
setNextReader in class AbstractFirstPassGroupingCollector<String>
Parameters:
reader - next IndexReader
Throws:
IOException


Copyright © 2000-2011 Apache Software Foundation. All Rights Reserved.