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:

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

Data Types:

Header --> CodecHeader (WriteHeader(DataOutput, string, int))
PackedType --> Byte (WriteByte(byte))
MaxAddress, MinValue, DefaultValue --> Int64 (WriteInt64(long))
PackedStream, Addresses, Ordinals --> PackedInt32s
ValueSize, NumValues --> Int32 (WriteInt32(int))
Float32 --> 32-bit float encoded with SingleToRawInt32Bits(float) then written as Int32 (WriteInt32(int))
Float64 --> 64-bit float encoded with DoubleToRawInt64Bits(double) then written as Int64 (WriteInt64(long))
TotalBytes --> VLong (WriteVInt64(long))
TotalVarBytes --> Int64 (WriteInt64(long))
LengthPrefix --> Length of the data value as VInt (WriteVInt32(int)) (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(int)) (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.
BYTES_VAR_STRAIGHT in contrast to other straight variants uses a .idx file to improve lookup perfromance. In contrast to 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

object

DocValuesFormat

Lucene40DocValuesFormat

Inherited Members

DocValuesFormat.SetDocValuesFormatFactory(IDocValuesFormatFactory)

DocValuesFormat.GetDocValuesFormatFactory()

DocValuesFormat.Name

DocValuesFormat.ToString()

DocValuesFormat.ForName(string)

DocValuesFormat.AvailableDocValuesFormats

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

Namespace: Lucene.Net.Codecs.Lucene40

Assembly: Lucene.Net.dll

Syntax

[Obsolete("Only for reading old 4.0 and 4.1 segments")]
[DocValuesFormatName("Lucene40")]
public class Lucene40DocValuesFormat : DocValuesFormat

Constructors

Lucene40DocValuesFormat()

Sole constructor.

Declaration

public Lucene40DocValuesFormat()

Fields

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
int

Methods

FieldsConsumer(SegmentWriteState)

Returns a DocValuesConsumer to write docvalues to the index.

Declaration

public override DocValuesConsumer FieldsConsumer(SegmentWriteState state)

Parameters

Type	Name	Description
SegmentWriteState	state

Returns

Type	Description
DocValuesConsumer

Overrides

DocValuesFormat.FieldsConsumer(SegmentWriteState)

FieldsProducer(SegmentReadState)

Returns a DocValuesProducer to read docvalues from the index.

NOTE: by the time this call returns, it must hold open any files it will need to use; else, those files may be deleted. Additionally, required files may be deleted during the execution of this call before there is a chance to open them. Under these circumstances an IOException should be thrown by the implementation. IOExceptions are expected and will automatically cause a retry of the segment opening logic with the newly revised segments.

Declaration

public override DocValuesProducer FieldsProducer(SegmentReadState state)

Parameters

Type	Name	Description
SegmentReadState	state

Returns

Type	Description
DocValuesProducer

Overrides

DocValuesFormat.FieldsProducer(SegmentReadState)