org.apache.lucene.codecs.lucene80

Class Lucene80NormsFormat

java.lang.Object

org.apache.lucene.codecs.NormsFormat

org.apache.lucene.codecs.lucene80.Lucene80NormsFormat

public class Lucene80NormsFormat
extends NormsFormat

Lucene 8.0 Score normalization format.

Encodes normalization values by encoding each value with the minimum number of bytes needed to represent the range (which can be zero).

Files:

1. .nvd: Norms data
2. .nvm: Norms metadata

1. The Norms metadata or .nvm file.

   For each norms field, this stores metadata, such as the offset into the Norms data (.nvd)

   Norms metadata (.dvm) --> Header,<Entry>^NumFields,Footer

   • Header --> IndexHeader
   • Entry --> FieldNumber, DocsWithFieldAddress, DocsWithFieldLength, NumDocsWithField, BytesPerNorm, NormsAddress
   • FieldNumber --> Int32
   • DocsWithFieldAddress --> Int64
   • DocsWithFieldLength --> Int64
   • NumDocsWithField --> Int32
   • BytesPerNorm --> byte
   • NormsAddress --> Int64
   • Footer --> CodecFooter

   FieldNumber of -1 indicates the end of metadata.

   NormsAddress is the pointer to the start of the data in the norms data (.nvd), or the singleton value when BytesPerValue = 0. If BytesPerValue is different from 0 then there are NumDocsWithField values to read at that offset.

   DocsWithFieldAddress is the pointer to the start of the bit set containing documents that have a norm in the norms data (.nvd), or -2 if no documents have a norm value, or -1 if all documents have a norm value.

   DocsWithFieldLength is the number of bytes used to encode the set of documents that have a norm.

2. The Norms data or .nvd file.

   For each Norms field, this stores the actual per-document data (the heavy-lifting)

   Norms data (.nvd) --> Header,< Data >^NumFields,Footer

   • Header --> IndexHeader
   • DocsWithFieldData --> Bit set of MaxDoc bits
   • NormsData --> byte^{NumDocsWithField * BytesPerValue}
   • Footer --> CodecFooter

WARNING: This API is experimental and might change in incompatible ways in the next release.

Constructor Summary

Constructors

Constructor and Description
Lucene80NormsFormat() Sole Constructor

Method Summary

Modifier and Type	Method and Description
NormsConsumer	normsConsumer(SegmentWriteState state) Returns a NormsConsumer to write norms to the index.
NormsProducer	normsProducer(SegmentReadState state) Returns a NormsProducer to read norms from the index.

Methods inherited from class java.lang.Object

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

Constructor Detail

Lucene80NormsFormat

public Lucene80NormsFormat()

Sole Constructor

Method Detail

normsConsumer

public NormsConsumer normsConsumer(SegmentWriteState state)
                            throws IOException

Description copied from class: NormsFormat

Returns a NormsConsumer to write norms to the index.

Specified by:

normsConsumer in class NormsFormat

Throws:

IOException

normsProducer

public NormsProducer normsProducer(SegmentReadState state)
                            throws IOException

Description copied from class: NormsFormat

Returns a NormsProducer to read norms 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:

normsProducer in class NormsFormat

Throws:

IOException