org.apache.lucene.codecs.lucene42

Class Lucene42FieldInfosFormat

java.lang.Object

org.apache.lucene.codecs.FieldInfosFormat

org.apache.lucene.codecs.lucene42.Lucene42FieldInfosFormat

public final class Lucene42FieldInfosFormat
extends FieldInfosFormat

Lucene 4.2 Field Infos format.

Field names are stored in the field info file, with suffix .fnm.

FieldInfos (.fnm) --> Header,FieldsCount, <FieldName,FieldNumber, FieldBits,DocValuesBits,Attributes> ^FieldsCount

Data types:

• Header --> CodecHeader
• FieldsCount --> VInt
• FieldName --> String
• FieldBits, DocValuesBits --> Byte
• FieldNumber --> VInt
• Attributes --> Map<String,String>

Field Descriptions:

• FieldsCount: the number of fields in this file.
• FieldName: name of the field as a UTF-8 String.
• FieldNumber: the field's number. Note that unlike previous versions of Lucene, the fields are not numbered implicitly by their order in the file, instead explicitly.
• FieldBits: a byte containing field options.
  • The low-order bit is one for indexed fields, and zero for non-indexed fields.
  • The second lowest-order bit is one for fields that have term vectors stored, and zero for fields without term vectors.
  • If the third lowest order-bit is set (0x4), offsets are stored into the postings list in addition to positions.
  • Fourth bit is unused.
  • If the fifth lowest-order bit is set (0x10), norms are omitted for the indexed field.
  • If the sixth lowest-order bit is set (0x20), payloads are stored for the indexed field.
  • If the seventh lowest-order bit is set (0x40), term frequencies and positions omitted for the indexed field.
  • If the eighth lowest-order bit is set (0x80), positions are omitted for the indexed field.
• DocValuesBits: a byte containing per-document value types. The type recorded as two four-bit integers, with the high-order bits representing norms options, and the low-order bits representing DocValues options. Each four-bit integer can be decoded as such:
  • 0: no DocValues for this field.
  • 1: NumericDocValues. (FieldInfo.DocValuesType.NUMERIC)
  • 2: BinaryDocValues. (DocValuesType#BINARY)
  • 3: SortedDocValues. (DocValuesType#SORTED)
• Attributes: a key-value map of codec-private attributes.

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

Constructor Summary

Constructors

Constructor and Description
Lucene42FieldInfosFormat() Sole constructor.

Method Summary

Methods

Modifier and Type	Method and Description
FieldInfosReader	getFieldInfosReader() Returns a FieldInfosReader to read field infos from the index
FieldInfosWriter	getFieldInfosWriter() Returns a FieldInfosWriter to write field infos to the index

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Lucene42FieldInfosFormat

public Lucene42FieldInfosFormat()

Sole constructor.

Method Detail

getFieldInfosReader

public FieldInfosReader getFieldInfosReader()
                                     throws IOException

Description copied from class: FieldInfosFormat

Returns a FieldInfosReader to read field infos from the index

Specified by:

getFieldInfosReader in class FieldInfosFormat

Throws:

IOException

getFieldInfosWriter

public FieldInfosWriter getFieldInfosWriter()
                                     throws IOException

Description copied from class: FieldInfosFormat

Returns a FieldInfosWriter to write field infos to the index

Specified by:

getFieldInfosWriter in class FieldInfosFormat

Throws:

IOException