Class ReverseOrdFieldSource

  extended by org.apache.lucene.queries.function.ValueSource
      extended by 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
 String field
Constructor Summary
ReverseOrdFieldSource(String field)
Method Summary
 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


public final String field
Constructor Detail


public ReverseOrdFieldSource(String field)
Method Detail


public String description()
Description copied from class: ValueSource
description of field, used in explain()

Specified by:
description in class ValueSource


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


public boolean equals(Object o)
Specified by:
equals in class ValueSource


public int hashCode()
Specified by:
hashCode in class ValueSource

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