Class AbstractFirstPassGroupingCollector<TGroupValue>

FirstPassGroupingCollector is the first of two passes necessary to collect grouped hits. This pass gathers the top N sorted groups. Concrete subclasses define what a group is and how it is internally collected.

See org.apache.lucene.search.grouping for more details including a full code example.

Note

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

Inheritance

object

AbstractFirstPassGroupingCollector<TGroupValue>

FunctionFirstPassGroupingCollector<TMutableValue>

TermFirstPassGroupingCollector

Implements

IAbstractFirstPassGroupingCollector<TGroupValue>

ICollector

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: Lucene.Net.Search.Grouping

Assembly: Lucene.Net.Grouping.dll

Syntax

public abstract class AbstractFirstPassGroupingCollector<TGroupValue> : IAbstractFirstPassGroupingCollector<TGroupValue>, ICollector

Type Parameters

Name	Description
TGroupValue

Constructors

AbstractFirstPassGroupingCollector(Sort, int)

Create the first pass collector.

Declaration

protected AbstractFirstPassGroupingCollector(Sort groupSort, int topNGroups)

Parameters

Type	Name	Description
Sort	groupSort	The Lucene.Net.Search.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.
int	topNGroups	How many top groups to keep.

Exceptions

Type	Condition
IOException	If I/O related errors occur

Fields

m_orderedGroups

FirstPassGroupingCollector is the first of two passes necessary to collect grouped hits. This pass gathers the top N sorted groups. Concrete subclasses define what a group is and how it is internally collected.

See org.apache.lucene.search.grouping for more details including a full code example.

Note

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

Declaration

protected SortedSet<CollectedSearchGroup<TGroupValue>> m_orderedGroups

Field Value

Type	Description
SortedSet<CollectedSearchGroup<TGroupValue>>

Properties

AcceptsDocsOutOfOrder

Return true if this collector does not require the matching docIDs to be delivered in int sort order (smallest to largest) to Collect(int).

Most Lucene Query implementations will visit matching docIDs in order. However, some queries (currently limited to certain cases of Lucene.Net.Search.BooleanQuery) can achieve faster searching if the Lucene.Net.Search.ICollector allows them to deliver the docIDs out of order.

Many collectors don't mind getting docIDs out of order, so it's important to return true here.

Declaration

public virtual bool AcceptsDocsOutOfOrder { get; }

Property Value

Type	Description
bool

Methods

Collect(int)

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 Lucene.Net.Search.CollectionTerminatedException. In this case, the last docs of the current Lucene.Net.Index.AtomicReaderContext will be skipped and Lucene.Net.Search.IndexSearcher 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 Doc(int) or Document(int) on every hit. Doing so can slow searches by an order of magnitude or more.

Declaration

public virtual void Collect(int doc)

Parameters

Type	Name	Description
int	doc

CopyDocGroupValue(TGroupValue, TGroupValue)

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.

Declaration

protected abstract TGroupValue CopyDocGroupValue(TGroupValue groupValue, TGroupValue reuse)

Parameters

Type	Name	Description
TGroupValue	groupValue	The group value to copy
TGroupValue	reuse	Optionally a reuse instance to prevent a new instance creation

Returns

Type	Description
TGroupValue	a copy of the specified group value

GetDocGroupValue(int)

Returns the group value for the specified doc.

Declaration

protected abstract TGroupValue GetDocGroupValue(int doc)

Parameters

Type	Name	Description
int	doc	The specified doc

Returns

Type	Description
TGroupValue	the group value for the specified doc

GetTopGroups(int, bool)

Returns top groups, starting from offset. This may return null, if no groups were collected, or if the number of unique groups collected is <= offset.

Declaration

public virtual IEnumerable<ISearchGroup<TGroupValue>> GetTopGroups(int groupOffset, bool fillFields)

Parameters

Type	Name	Description
int	groupOffset	The offset in the collected groups
bool	fillFields	Whether to fill to SortValues

Returns

Type	Description
IEnumerable<ISearchGroup<TGroupValue>>	top groups, starting from offset

SetNextReader(AtomicReaderContext)

Called before collecting from each Lucene.Net.Index.AtomicReaderContext. All doc ids in Collect(int) will correspond to Lucene.Net.Index.IndexReaderContext.Reader.

Add Lucene.Net.Index.AtomicReaderContext.DocBase to the current Lucene.Net.Index.IndexReaderContext.Reader's internal document id to re-base ids in Collect(int).

Declaration

public virtual void SetNextReader(AtomicReaderContext context)

Parameters

Type	Name	Description
AtomicReaderContext	context	next atomic reader context

SetScorer(Scorer)

Called before successive calls to Collect(int). Implementations that need the score of the current document (passed-in to Collect(int)), should save the passed-in Lucene.Net.Search.Scorer and call scorer.GetScore() when needed.

Declaration

public virtual void SetScorer(Scorer scorer)

Parameters

Type	Name	Description
Scorer	scorer

Implements

IAbstractFirstPassGroupingCollector<TGroupValue>

Lucene.Net.Search.ICollector