com.yahoo.prelude.query

Class WandItem

java.lang.Object

com.yahoo.prelude.query.Item

com.yahoo.prelude.query.SimpleTaggableItem

com.yahoo.prelude.query.WeightedSetItem

com.yahoo.prelude.query.WandItem

All Implemented Interfaces:

TaggableItem, Cloneable

public class WandItem
extends WeightedSetItem

A weighted set query item to be evaluated as a Wand with dot product scoring. The dot product is calculated between the matched tokens of the weighted set field searched and the weights associated with the tokens of this WandItem. The resulting dot product will be available as a raw score in the rank framework.

Since:

5.1.27

Author:

geirst

Nested Class Summary

Nested classes/interfaces inherited from class com.yahoo.prelude.query.Item

Item.ItemCreator, Item.ItemType

Field Summary

Fields

Modifier and Type	Field and Description
private double	scoreThreshold
private int	targetNumHits
private double	thresholdBoostFactor

Fields inherited from class com.yahoo.prelude.query.Item

connectedBacklink, connectedItem, connectivity, DEFAULT_WEIGHT, explicitSignificance, significance, uniqueID

Constructor Summary

Constructors

Constructor and Description
WandItem(String fieldName, int targetNumHits) Creates an empty WandItem.

Method Summary

Modifier and Type	Method and Description
protected void	appendHeadingString(StringBuilder buffer) Appends the heading of this string.
void	disclose(Discloser discloser)
protected void	encodeThis(ByteBuffer buffer)
Item.ItemType	getItemType() Return the enumerated type of this item.
double	getScoreThreshold()
int	getTargetNumHits()
double	getThresholdBoostFactor()
void	setScoreThreshold(double scoreThreshold) Sets the initial score threshold used by the backend search operator handling this WandItem.
void	setThresholdBoostFactor(double thresholdBoostFactor) Sets the boost factor used by the backend search operator to boost the threshold before comparing it with the upper bound score of the document being evaluated.

Methods inherited from class com.yahoo.prelude.query.WeightedSetItem

addToken, addToken, addToken, appendBodyString, clone, encode, getIndexName, getName, getNumTokens, getTermCount, getTokens, getTokenWeight, removeToken, setIndexName

Methods inherited from class com.yahoo.prelude.query.SimpleTaggableItem

getConnectedItem, getConnectivity, getSignificance, getUniqueID, hasExplicitSignificance, hasUniqueID, setConnectivity, setExplicitSignificance, setSignificance, setUniqueID

Methods inherited from class com.yahoo.prelude.query.Item

addAnnotation, equals, getAnnotation, getBytes, getCode, getCreator, getLabel, getLanguage, getParent, getWeight, hasAnnotation, hasConnectivityBackLink, hashCode, isFilter, isFromSpecialToken, isProtected, isRanked, isRoot, putBytes, putString, setCreator, setFilter, setFromSpecialToken, setHasUniqueID, setLabel, setLanguage, setParent, setPositionData, setProtected, setRanked, setWeight, shouldParenthize, toString, usePositionData

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

targetNumHits

private int targetNumHits

scoreThreshold

private double scoreThreshold

thresholdBoostFactor

private double thresholdBoostFactor

Constructor Detail

WandItem

public WandItem(String fieldName,
                int targetNumHits)

Creates an empty WandItem.

Parameters:

fieldName - The name of the weighted set field to search with this WandItem.

targetNumHits - The target for minimum number of hits to produce by the backend search operator handling this WandItem.

Method Detail

setScoreThreshold

public void setScoreThreshold(double scoreThreshold)

Sets the initial score threshold used by the backend search operator handling this WandItem. The score of a document must be larger than this threshold in order to be considered a match. Default value is 0.0.

Parameters:

scoreThreshold - the initial score threshold.

setThresholdBoostFactor

public void setThresholdBoostFactor(double thresholdBoostFactor)

Sets the boost factor used by the backend search operator to boost the threshold before comparing it with the upper bound score of the document being evaluated. A large value of this factor results in fewer full evaluations and in an expected loss in precision. Similarly, a gain in performance might be expected. Default value is 1.0. NOTE: This boost factor is only used when this WandItem is searching a Vespa field.

Parameters:

thresholdBoostFactor - the boost factor.

getTargetNumHits

public int getTargetNumHits()

getScoreThreshold

public double getScoreThreshold()

getThresholdBoostFactor

public double getThresholdBoostFactor()

getItemType

public Item.ItemType getItemType()

Description copied from class: Item

Return the enumerated type of this item.

Overrides:

getItemType in class WeightedSetItem

encodeThis

protected void encodeThis(ByteBuffer buffer)

Overrides:

encodeThis in class WeightedSetItem

appendHeadingString

protected void appendHeadingString(StringBuilder buffer)

Description copied from class: Item

Appends the heading of this string. As default getName() followed by a space.

Overrides:

appendHeadingString in class Item

disclose

public void disclose(Discloser discloser)

Overrides:

disclose in class WeightedSetItem