## 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
`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

### 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`

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