Class OrdFieldSource

Obtains the ordinal of the field value from the default Lucene FieldCache using StringIndex.

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:

    If there were only three field values: "apple","banana","pear"
    then ord("apple")=1, ord("banana")=2, ord("pear")=3

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.