Class Lucene40DocValuesFormat

Lucene 4.0 DocValues format.

Files:

.dv.cfs: compound container (CompoundFileDirectory)
.dv.cfe: compound entries (CompoundFileDirectory)

Entries within the compound file:

<segment><fieldNumber>.dat: data values
<segment><fieldNumber>.idx: index into the .dat for DEREF types

There are several many types of DocValues with different encodings. From the perspective of filenames, all types store their values in .dat entries within the compound file. In the case of dereferenced/sorted types, the .dat actually contains only the unique values, and an additional .idx file contains pointers to these unique values.

Formats:

Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.VAR_INTS .dat --> Header, PackedType, MinValue, DefaultValue, PackedStream
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.FIXED_INTS_8 .dat --> Header, ValueSize, Byte (WriteByte(Byte)) ^maxdoc
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.FIXED_INTS_16 .dat --> Header, ValueSize, Short (WriteInt16(Int16)) ^maxdoc
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.FIXED_INTS_32 .dat --> Header, ValueSize, Int32 (WriteInt32(Int32)) ^maxdoc
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.FIXED_INTS_64 .dat --> Header, ValueSize, Int64 (WriteInt64(Int64)) ^maxdoc
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.FLOAT_32 .dat --> Header, ValueSize, Float32^maxdoc
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.FLOAT_64 .dat --> Header, ValueSize, Float64^maxdoc
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_FIXED_STRAIGHT .dat --> Header, ValueSize, (Byte (WriteByte(Byte)) * ValueSize)^maxdoc
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_VAR_STRAIGHT .idx --> Header, TotalBytes, Addresses
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_VAR_STRAIGHT .dat --> Header, (Byte (WriteByte(Byte)) * variable ValueSize)^maxdoc
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_FIXED_DEREF .idx --> Header, NumValues, Addresses
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_FIXED_DEREF .dat --> Header, ValueSize, (Byte (WriteByte(Byte)) * ValueSize)^NumValues
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_VAR_DEREF .idx --> Header, TotalVarBytes, Addresses
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_VAR_DEREF .dat --> Header, (LengthPrefix + Byte (WriteByte(Byte)) * variable ValueSize)^NumValues
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_FIXED_SORTED .idx --> Header, NumValues, Ordinals
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_FIXED_SORTED .dat --> Header, ValueSize, (Byte (WriteByte(Byte)) * ValueSize)^NumValues
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_VAR_SORTED .idx --> Header, TotalVarBytes, Addresses, Ordinals
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_VAR_SORTED .dat --> Header, (Byte (WriteByte(Byte)) * variable ValueSize)^NumValues

Data Types:

Header --> CodecHeader (WriteHeader(DataOutput, String, Int32))
PackedType --> Byte (WriteByte(Byte))
MaxAddress, MinValue, DefaultValue --> Int64 (WriteInt64(Int64))
PackedStream, Addresses, Ordinals --> PackedInt32s
ValueSize, NumValues --> Int32 (WriteInt32(Int32))
Float32 --> 32-bit float encoded with then written as Int32 (WriteInt32(Int32))
Float64 --> 64-bit float encoded with then written as Int64 (WriteInt64(Int64))
TotalBytes --> VLong (WriteVInt64(Int64))
TotalVarBytes --> Int64 (WriteInt64(Int64))
LengthPrefix --> Length of the data value as VInt (WriteVInt32(Int32)) (maximum of 2 bytes)

Notes:

PackedType is a 0 when compressed, 1 when the stream is written as 64-bit integers.
Addresses stores pointers to the actual byte location (indexed by docid). In the VAR_STRAIGHT case, each entry can have a different length, so to determine the length, docid+1 is retrieved. A sentinel address is written at the end for the VAR_STRAIGHT case, so the Addresses stream contains maxdoc+1 indices. For the deduplicated VAR_DEREF case, each length is encoded as a prefix to the data itself as a VInt (WriteVInt32(Int32)) (maximum of 2 bytes).
Ordinals stores the term ID in sorted order (indexed by docid). In the FIXED_SORTED case, the address into the .dat can be computed from the ordinal as Header+ValueSize+(ordinal*ValueSize) because the byte length is fixed. In the VAR_SORTED case, there is double indirection (docid -> ordinal -> address), but an additional sentinel ordinal+address is always written (so there are NumValues+1 ordinals). To determine the length, ord+1's address is looked up as well.
Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_VAR_STRAIGHT in contrast to other straight variants uses a .idx file to improve lookup perfromance. In contrast to Lucene.Net.Codecs.Lucene40.LegacyDocValuesType.BYTES_VAR_DEREF it doesn't apply deduplication of the document values.

Limitations:

Binary doc values can be at most MAX_BINARY_FIELD_LENGTH in length.

Inheritance

System.Object

DocValuesFormat

Lucene40DocValuesFormat

Inherited Members

DocValuesFormat.SetDocValuesFormatFactory(IDocValuesFormatFactory)

DocValuesFormat.GetDocValuesFormatFactory()

DocValuesFormat.Name

DocValuesFormat.ToString()

DocValuesFormat.ForName(String)

DocValuesFormat.AvailableDocValuesFormats

Namespace: Lucene.Net.Codecs.Lucene40

Assembly: Lucene.Net.dll

Syntax

public class Lucene40DocValuesFormat : DocValuesFormat

Constructors

| Improve this Doc View Source

Lucene40DocValuesFormat()

Sole constructor.

Declaration

public Lucene40DocValuesFormat()

Fields

| Improve this Doc View Source

MAX_BINARY_FIELD_LENGTH

Maximum length for each binary doc values field.

Declaration

public static readonly int MAX_BINARY_FIELD_LENGTH

Field Value

Type	Description
System.Int32

Methods

| Improve this Doc View Source

FieldsConsumer(SegmentWriteState)

Declaration

public override DocValuesConsumer FieldsConsumer(SegmentWriteState state)

Parameters

Type	Name	Description
SegmentWriteState	state

Returns

Type	Description
DocValuesConsumer

Overrides

DocValuesFormat.FieldsConsumer(SegmentWriteState)

| Improve this Doc View Source

FieldsProducer(SegmentReadState)

Declaration

public override DocValuesProducer FieldsProducer(SegmentReadState state)

Parameters

Type	Name	Description
SegmentReadState	state

Returns

Type	Description
DocValuesProducer

Overrides

DocValuesFormat.FieldsProducer(SegmentReadState)