Class Lucene40DocValuesFormat

  • All Implemented Interfaces:

    public class Lucene40DocValuesFormat
    extends DocValuesFormat
    Only for reading old 4.0 and 4.1 segments
    Lucene 4.0 DocValues format.


    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.

    • VAR_INTS .dat --> Header, PackedType, MinValue, DefaultValue, PackedStream
    • FIXED_INTS_8 .dat --> Header, ValueSize, Bytemaxdoc
    • FIXED_INTS_16 .dat --> Header, ValueSize, Shortmaxdoc
    • FIXED_INTS_32 .dat --> Header, ValueSize, Int32maxdoc
    • FIXED_INTS_64 .dat --> Header, ValueSize, Int64maxdoc
    • FLOAT_32 .dat --> Header, ValueSize, Float32maxdoc
    • FLOAT_64 .dat --> Header, ValueSize, Float64maxdoc
    • BYTES_FIXED_STRAIGHT .dat --> Header, ValueSize, (Byte * ValueSize)maxdoc
    • BYTES_VAR_STRAIGHT .idx --> Header, TotalBytes, Addresses
    • BYTES_VAR_STRAIGHT .dat --> Header, (Byte * variable ValueSize)maxdoc
    • BYTES_FIXED_DEREF .idx --> Header, NumValues, Addresses
    • BYTES_FIXED_DEREF .dat --> Header, ValueSize, (Byte * ValueSize)NumValues
    • BYTES_VAR_DEREF .idx --> Header, TotalVarBytes, Addresses
    • BYTES_VAR_DEREF .dat --> Header, (LengthPrefix + Byte * variable ValueSize)NumValues
    • BYTES_FIXED_SORTED .idx --> Header, NumValues, Ordinals
    • BYTES_FIXED_SORTED .dat --> Header, ValueSize, (Byte * ValueSize)NumValues
    • BYTES_VAR_SORTED .idx --> Header, TotalVarBytes, Addresses, Ordinals
    • BYTES_VAR_SORTED .dat --> Header, (Byte * variable ValueSize)NumValues
    Data Types:
    • Header --> CodecHeader
    • PackedType --> Byte
    • MaxAddress, MinValue, DefaultValue --> Int64
    • PackedStream, Addresses, Ordinals --> PackedInts
    • ValueSize, NumValues --> Int32
    • Float32 --> 32-bit float encoded with Float.floatToRawIntBits(float) then written as Int32
    • Float64 --> 64-bit float encoded with Double.doubleToRawLongBits(double) then written as Int64
    • TotalBytes --> VLong
    • TotalVarBytes --> Int64
    • LengthPrefix --> Length of the data value as VInt (maximum of 2 bytes)
    • 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 (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 BYTES_VAR_STRAIGHT in contrast to other straight variants uses a .idx file to improve lookup perfromance. In contrast to BYTES_VAR_DEREF BYTES_VAR_DEREF it doesn't apply deduplication of the document values.


    • Field Detail


        public static final int MAX_BINARY_FIELD_LENGTH
        Maximum length for each binary doc values field.
        See Also:
        Constant Field Values
    • Constructor Detail

      • Lucene40DocValuesFormat

        public Lucene40DocValuesFormat()
        Sole constructor.
    • Method Detail

      • fieldsProducer

        public DocValuesProducer fieldsProducer​(SegmentReadState state)
        Description copied from class: DocValuesFormat
        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.

        Specified by:
        fieldsProducer in class DocValuesFormat