Class 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.