Class Lucene46FieldInfosFormat

Lucene 4.6 Field Infos format.

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

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

Data types:

• Header --> CodecHeader (WriteHeader(DataOutput, String, Int32))
• FieldsCount --> VInt (WriteVInt32(Int32))
• FieldName --> String (WriteString(String))
• FieldBits, DocValuesBits --> Byte (WriteByte(Byte))
• FieldNumber --> VInt (WriteInt32(Int32))
• Attributes --> IDictionary<String,String> ()
• DocValuesGen --> Int64 (WriteInt64(Int64))
• Footer --> CodecFooter (WriteFooter(IndexOutput))

• 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 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 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. (NUMERIC)
  • 2: BinaryDocValues. (BINARY)
  • 3: SortedDocValues. (SORTED)
• DocValuesGen is the generation count of the field's DocValues. If this is -1, there are no DocValues updates to that field. Anything above zero means there are updates stored by DocValuesFormat.
• Attributes: a key-value map of codec-private attributes.

@lucene.experimental