org.apache.lucene.search.function
Class OrdFieldSource

java.lang.Object
  org.apache.lucene.search.function.ValueSource
      org.apache.lucene.search.function.OrdFieldSource

All Implemented Interfaces:

Serializable

public class OrdFieldSource
extends ValueSource

Expert: obtains the ordinal of the field value from the default Lucene Fieldcache using getStringIndex().

The native lucene index order is used to assign an ordinal value for each field value.

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: The status of the search.function package is experimental. The APIs introduced here might change in the future and will not be supported anymore in such a case.

NOTE: with the switch in 2.9 to segment-based searching, if getValues(org.apache.lucene.index.IndexReader) is invoked with a composite (multi-segment) reader, this can easily cause double RAM usage for the values in the FieldCache. It's best to switch your application to pass only atomic (single segment) readers to this API.

See Also:

Serialized Form

Field Summary

protected String

field

Constructor Summary

OrdFieldSource(String field)
Constructor for a certain field.

Method Summary

String	description() description of field, used in explain()
boolean	equals(Object o) Needed for possible caching of query results - used by ValueSourceQuery.equals(Object).
DocValues	getValues(IndexReader reader) Return the DocValues used by the function query.
int	hashCode() Needed for possible caching of query results - used by ValueSourceQuery.hashCode().

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

toString

Methods inherited from class java.lang.Object

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

Field Detail

field

protected String field

Constructor Detail

OrdFieldSource

public OrdFieldSource(String field)

Constructor for a certain field.

Parameters:

field - field whose values order is used.

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 DocValues getValues(IndexReader reader)
                    throws IOException

Description copied from class: ValueSource

Return the DocValues used by the function query.

Specified by:

getValues in class ValueSource

Parameters:

reader - the IndexReader used to read these values. If any caching is involved, that caching would also be IndexReader based.

Throws:

IOException - for any error.

equals

public boolean equals(Object o)

Description copied from class: ValueSource

Needed for possible caching of query results - used by ValueSourceQuery.equals(Object).

Specified by:

equals in class ValueSource

See Also:

Object.equals(Object)

hashCode

public int hashCode()

Description copied from class: ValueSource

Needed for possible caching of query results - used by ValueSourceQuery.hashCode().

Specified by:

hashCode in class ValueSource

See Also:

Object.hashCode()