org.apache.lucene.queries.function.valuesource

Class ReverseOrdFieldSource

java.lang.Object

org.apache.lucene.queries.function.ValueSource

org.apache.lucene.queries.function.valuesource.ReverseOrdFieldSource

public class ReverseOrdFieldSource
extends ValueSource

Obtains the ordinal of the field value from the default Lucene FieldCache using getTermsIndex() and reverses the order.
The native lucene index order is used to assign an ordinal value for each field value.
Field values (terms) are lexicographically ordered by unicode value, and numbered starting at 1.
Example of reverse ordinal (rord):
If there were only three field values: "apple","banana","pear"
then rord("apple")=3, rord("banana")=2, ord("pear")=1

WARNING: ord() depends on the position in an index and can thus change when other documents are inserted or deleted, or if a MultiSearcher is used.
WARNING: as of Solr 1.4, ord() and rord() can cause excess memory use since they must use a FieldCache entry at the top level reader, while sorting and function queries now use entries at the segment level. Hence sorting or using a different function query, in addition to ord()/rord() will double memory use.

Field Summary

Fields

Modifier and Type	Field and Description
String	field

Constructor Summary

Constructors

Constructor and Description
ReverseOrdFieldSource(String field)

Method Summary

Methods

Modifier and Type	Method and Description
String	description() description of field, used in explain()
boolean	equals(Object o)
FunctionValues	getValues(Map context, AtomicReaderContext readerContext) Gets the values for this reader and the context that was previously passed to createWeight()
int	hashCode()

Methods inherited from class org.apache.lucene.queries.function.ValueSource

createWeight, getSortField, newContext, toString

Methods inherited from class java.lang.Object

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

Field Detail

field

public final String field

Constructor Detail

ReverseOrdFieldSource

public ReverseOrdFieldSource(String field)

Method Detail

description

public String description()

Description copied from class: ValueSource

description of field, used in explain()

Specified by:

description in class ValueSource

getValues

public FunctionValues getValues(Map context,
                       AtomicReaderContext readerContext)
                         throws IOException

Description copied from class: ValueSource

Gets the values for this reader and the context that was previously passed to createWeight()

Specified by:

getValues in class ValueSource

Throws:

IOException

equals

public boolean equals(Object o)

Specified by:

equals in class ValueSource

hashCode

public int hashCode()

Specified by:

hashCode in class ValueSource