Class MultiCollector

A ICollector which allows running a search with several ICollectors. It offers a static Wrap(params ICollector[]) method which accepts a list of collectors and wraps them with MultiCollector, while filtering out the null ones.

Inheritance

object

MultiCollector

Implements

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

Assembly: Lucene.Net.dll

Syntax

public class MultiCollector : ICollector

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 BooleanQuery) can achieve faster searching if the 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 CollectionTerminatedException. In this case, the last docs of the current AtomicReaderContext will be skipped and 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

SetNextReader(AtomicReaderContext)

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

Add DocBase to the current 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 Scorer and call scorer.GetScore() when needed.

Declaration

public virtual void SetScorer(Scorer scorer)

Parameters

Type	Name	Description
Scorer	scorer

Wrap(params ICollector[])

Wraps a list of ICollectors with a MultiCollector. This method works as follows:

• Filters out the null collectors, so they are not used during search time.
• If the input contains 1 real collector (i.e. non-null ), it is returned.
• Otherwise the method returns a MultiCollector which wraps the non-

  null

  ones.

Declaration

public static ICollector Wrap(params ICollector[] collectors)

Parameters

Type	Name	Description
ICollector[]	collectors

Returns

Type	Description
ICollector

Exceptions

Type	Condition
ArgumentException	if either 0 collectors were input, or all collectors are null.

Implements

ICollector