org.apache.lucene.search.function
Class FieldCacheSource

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

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

ByteFieldSource, FloatFieldSource, IntFieldSource, ShortFieldSource

public abstract class FieldCacheSource
extends ValueSource

Expert: A base class for ValueSource implementations that retrieve values for a single field from the FieldCache.

Fields used herein must be indexed (doesn't matter if these fields are stored or not).

It is assumed that each such indexed field is untokenized, or at least has a single token in a document. For documents with multiple tokens of the same field, behavior is undefined (It is likely that current code would use the value of one of these tokens, but this is not guaranteed).

Document with no tokens in this field are assigned the Zero value.

See Also:

Serialized Form

WARNING: This API is experimental and might change in incompatible ways in the next release.

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.

Constructor Summary

FieldCacheSource(String field)
Create a cached field source for the input field.

Method Summary

abstract boolean	cachedFieldSourceEquals(FieldCacheSource other) Check if equals to another FieldCacheSource, already knowing that cache and field are equal.
abstract int	cachedFieldSourceHashCode() Return a hash code of a FieldCacheSource, without the hash-codes of the field and the cache (those are taken care of elsewhere).
String	description() description of field, used in explain()
boolean	equals(Object o) Needed for possible caching of query results - used by ValueSourceQuery.equals(Object).
abstract DocValues	getCachedFieldValues(FieldCache cache, String field, IndexReader reader) Return cached DocValues for input field and reader.
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

Constructor Detail

FieldCacheSource

public FieldCacheSource(String field)

Create a cached field source for the input field.

Method Detail

getValues

public final 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.

description

public String description()

Description copied from class: ValueSource

description of field, used in explain()

Specified by:

description in class ValueSource

getCachedFieldValues

public abstract DocValues getCachedFieldValues(FieldCache cache,
                                               String field,
                                               IndexReader reader)
                                        throws IOException

Return cached DocValues for input field and reader.

Parameters:

cache - FieldCache so that values of a field are loaded once per reader (RAM allowing)

field - Field for which values are required.

Throws:

IOException

See Also:

ValueSource

equals

public final 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 final 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()

cachedFieldSourceEquals

public abstract boolean cachedFieldSourceEquals(FieldCacheSource other)

Check if equals to another FieldCacheSource, already knowing that cache and field are equal.

See Also:

Object.equals(java.lang.Object)

cachedFieldSourceHashCode

public abstract int cachedFieldSourceHashCode()

Return a hash code of a FieldCacheSource, without the hash-codes of the field and the cache (those are taken care of elsewhere).

See Also:

Object.hashCode()