Class TermFirstPassGroupingCollector
- java.lang.Object
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- org.apache.lucene.search.Collector
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- org.apache.lucene.search.grouping.AbstractFirstPassGroupingCollector<String>
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- org.apache.lucene.search.grouping.TermFirstPassGroupingCollector
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public class TermFirstPassGroupingCollector extends AbstractFirstPassGroupingCollector<String>
Concrete implementation ofAbstractFirstPassGroupingCollector
that groups based on field values and more specifically usesFieldCache.StringIndex
to collect groups.- WARNING: This API is experimental and might change in incompatible ways in the next release.
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Constructor Summary
Constructors Constructor Description TermFirstPassGroupingCollector(String groupField, Sort groupSort, int topNGroups)
Create the first pass collector.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description 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
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Constructor Detail
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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
- 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.- Throws:
IOException
- When I/O related errors occur
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Method Detail
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getDocGroupValue
protected String getDocGroupValue(int doc)
Description copied from class:AbstractFirstPassGroupingCollector
Returns the group value for the specified doc.- Specified by:
getDocGroupValue
in classAbstractFirstPassGroupingCollector<String>
- Parameters:
doc
- The specified doc- Returns:
- the group value for the specified doc
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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 classAbstractFirstPassGroupingCollector<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
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setNextReader
public void setNextReader(IndexReader reader, int docBase) throws IOException
Description copied from class:Collector
Called before collecting from each IndexReader. All doc ids inCollector.collect(int)
will correspond to reader. Add docBase to the current IndexReaders internal document id to re-base ids inCollector.collect(int)
.- Overrides:
setNextReader
in classAbstractFirstPassGroupingCollector<String>
- Parameters:
reader
- next IndexReader- Throws:
IOException
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