Class Lucene40FieldInfosFormat

Lucene 4.0 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 (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> ()

• 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: variable-width signed integers. (Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.VAR_INTS)
  • 2: 32-bit floating point values. (Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.FLOAT_32)
  • 3: 64-bit floating point values. (Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.FLOAT_64)
  • 4: fixed-length byte array values. (Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_FIXED_STRAIGHT)
  • 5: fixed-length dereferenced byte array values. (Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_FIXED_DEREF)
  • 6: variable-length byte array values. (Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_VAR_STRAIGHT)
  • 7: variable-length dereferenced byte array values. (Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_VAR_DEREF)
  • 8: 16-bit signed integers. (Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.FIXED_INTS_16)
  • 9: 32-bit signed integers. (Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.FIXED_INTS_32)
  • 10: 64-bit signed integers. (Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.FIXED_INTS_64)
  • 11: 8-bit signed integers. (Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.FIXED_INTS_8)
  • 12: fixed-length sorted byte array values. (Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_FIXED_SORTED)
  • 13: variable-length sorted byte array values. (Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_VAR_SORTED)
• Attributes: a key-value map of codec-private attributes.

@lucene.experimental