Package org.apache.lucene.codecs.lucene40

Class Lucene40StoredFieldsFormat

java.lang.Object

org.apache.lucene.codecs.StoredFieldsFormat

org.apache.lucene.codecs.lucene40.Lucene40StoredFieldsFormat

public class Lucene40StoredFieldsFormat
extends StoredFieldsFormat

Lucene 4.0 Stored Fields Format.

Stored fields are represented by two files:

1. The field index, or .fdx file.

   This is used to find the location within the field data file of the fields of a particular document. Because it contains fixed-length data, this file may be easily randomly accessed. The position of document n 's field data is the Uint64 at n*8 in this file.

   This contains, for each document, a pointer to its field data, as follows:

   • FieldIndex (.fdx) --> <Header>, <FieldValuesPosition> ^SegSize
   • Header --> CodecHeader
   • FieldValuesPosition --> Uint64

2. The field data, or .fdt file.

   This contains the stored fields of each document, as follows:

   • FieldData (.fdt) --> <Header>, <DocFieldData> ^SegSize
   • Header --> CodecHeader
   • DocFieldData --> FieldCount, <FieldNum, Bits, Value> ^FieldCount
   • FieldCount --> VInt
   • FieldNum --> VInt
   • Bits --> Byte
   • low order bit reserved.
   • second bit is one for fields containing binary data
   • third bit reserved.
   • 4th to 6th bit (mask: 0x7<<3) define the type of a numeric field:
     • all bits in mask are cleared if no numeric field at all
     • 1<<3: Value is Int
     • 2<<3: Value is Long
     • 3<<3: Value is Int as Float (as of Float.intBitsToFloat(int)
     • 4<<3: Value is Long as Double (as of Double.longBitsToDouble(long)
   • Value --> String | BinaryValue | Int | Long (depending on Bits)
   • BinaryValue --> ValueSize, <Byte>^ValueSize
   • ValueSize --> VInt

Constructor Summary

Constructors

Constructor	Description
Lucene40StoredFieldsFormat()	Sole constructor.

Method Summary

Modifier and Type	Method	Description
StoredFieldsReader	fieldsReader(Directory directory, SegmentInfo si, FieldInfos fn, IOContext context)	Returns a StoredFieldsReader to load stored fields.
StoredFieldsWriter	fieldsWriter(Directory directory, SegmentInfo si, IOContext context)	Returns a StoredFieldsWriter to write stored fields.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Lucene40StoredFieldsFormat

public Lucene40StoredFieldsFormat()

Sole constructor.

Method Detail

fieldsReader

public StoredFieldsReader fieldsReader(Directory directory,
                                       SegmentInfo si,
                                       FieldInfos fn,
                                       IOContext context)
                                throws java.io.IOException

Description copied from class: StoredFieldsFormat

Returns a StoredFieldsReader to load stored fields.

Specified by:

fieldsReader in class StoredFieldsFormat

Throws:

java.io.IOException

fieldsWriter

public StoredFieldsWriter fieldsWriter(Directory directory,
                                       SegmentInfo si,
                                       IOContext context)
                                throws java.io.IOException

Description copied from class: StoredFieldsFormat

Returns a StoredFieldsWriter to write stored fields.

Specified by:

fieldsWriter in class StoredFieldsFormat

Throws:

java.io.IOException