org.apache.lucene.search.grouping
Class TermFirstPassGroupingCollector
java.lang.Object
org.apache.lucene.search.Collector
org.apache.lucene.search.grouping.AbstractFirstPassGroupingCollector<String>
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.
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(org.apache.lucene.index.IndexReader reader,
int docBase)
|
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
TermFirstPassGroupingCollector
public TermFirstPassGroupingCollector(String groupField,
org.apache.lucene.search.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
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 copyreuse
- Optionally a reuse instance to prevent a new instance creation
- Returns:
- a copy of the specified group value
setNextReader
public void setNextReader(org.apache.lucene.index.IndexReader reader,
int docBase)
throws IOException
- Overrides:
setNextReader
in class AbstractFirstPassGroupingCollector<String>
- Throws:
IOException
Copyright © 2000-2011 Apache Software Foundation. All Rights Reserved.