Package org.apache.lucene.codecs

Codecs API: API for customization of the encoding and structure of the index.

The Codec API allows you to customise the way the following pieces of index information are stored:

• Postings lists - see PostingsFormat
• DocValues - see DocValuesFormat
• Stored fields - see StoredFieldsFormat
• Term vectors - see TermVectorsFormat
• Points - see PointsFormat
• FieldInfos - see FieldInfosFormat
• SegmentInfo - see SegmentInfoFormat
• Norms - see NormsFormat
• Live documents - see LiveDocsFormat

For some concrete implementations beyond Lucene's official index format, see the Codecs module.

Codecs are identified by name through the Java Service Provider Interface. To create your own codec, extend Codec and pass the new codec's name to the super() constructor:

 public class MyCodec extends Codec {

     public MyCodec() {
         super("MyCodecName");
     }

     ...
 }
 

You will need to register the Codec class so that the ServiceLoader can find it, by including a META-INF/services/org.apache.lucene.codecs.Codec file on your classpath that contains the package-qualified name of your codec.

If you just want to customise the PostingsFormat, or use different postings formats for different fields, then you can register your custom postings format in the same way (in META-INF/services/org.apache.lucene.codecs.PostingsFormat), and then extend the default codec and override org.apache.lucene.codecs.luceneMN.LuceneMNCodec#getPostingsFormatForField(String) to return your custom postings format.

Similarly, if you just want to customise the DocValuesFormat per-field, have a look at LuceneMNCodec.getDocValuesFormatForField(String).

Class Summary

Class	Description
BlockTermState	Holds all state required for PostingsReaderBase to produce a PostingsEnum without re-seeking the terms dict.
Codec	Encodes/decodes an inverted index segment.
CodecUtil	Utility class for reading and writing versioned headers.
CompetitiveImpactAccumulator	This class accumulates the (freq, norm) pairs that may produce competitive scores.
CompoundDirectory	A read-only Directory that consists of a view over a compound file.
CompoundFormat	Encodes/decodes compound files
DocValuesConsumer	Abstract API that consumes numeric, binary and sorted docvalues.
DocValuesFormat	Encodes/decodes per-document values.
DocValuesProducer	Abstract API that produces numeric, binary, sorted, sortedset, and sortednumeric docvalues.
FieldInfosFormat	Encodes/decodes FieldInfos
FieldsConsumer	Abstract API that consumes terms, doc, freq, prox, offset and payloads postings.
FieldsProducer	Abstract API that produces terms, doc, freq, prox, offset and payloads postings.
FilterCodec	A codec that forwards all its method calls to another codec.
KnnVectorsFormat	Encodes/decodes per-document vector and any associated indexing structures required to support nearest-neighbor search
KnnVectorsReader	Reads vectors from an index.
KnnVectorsWriter	Writes vectors to an index.
LiveDocsFormat	Format for live/deleted documents
MultiLevelSkipListReader	This abstract class reads skip lists with multiple levels.
MultiLevelSkipListWriter	This abstract class writes skip lists with multiple levels.
MutablePointValues	PointValues whose order of points can be changed.
NormsConsumer	Abstract API that consumes normalization values.
NormsFormat	Encodes/decodes per-document score normalization values.
NormsProducer	Abstract API that produces field normalization values
PointsFormat	Encodes/decodes indexed points.
PointsReader	Abstract API to visit point values.
PointsWriter	Abstract API to write points
PostingsFormat	Encodes/decodes terms, postings, and proximity data.
PostingsReaderBase	The core terms dictionaries (BlockTermsReader, BlockTreeTermsReader) interact with a single instance of this class to manage creation of PostingsEnum and PostingsEnum instances.
PostingsWriterBase	Class that plugs into term dictionaries, such as Lucene90BlockTreeTermsWriter, and handles writing postings.
PushPostingsWriterBase	Extension of PostingsWriterBase, adding a push API for writing each element of the postings.
SegmentInfoFormat	Expert: Controls the format of the SegmentInfo (segment metadata file).
StoredFieldsFormat	Controls the format of stored fields
StoredFieldsReader	Codec API for reading stored fields.
StoredFieldsWriter	Codec API for writing stored fields: For every document, StoredFieldsWriter.startDocument() is called, informing the Codec that a new document has started.
TermStats	Holder for per-term statistics.
TermVectorsFormat	Controls the format of term vectors
TermVectorsReader	Codec API for reading term vectors:
TermVectorsWriter	Codec API for writing term vectors: For every document, TermVectorsWriter.startDocument(int) is called, informing the Codec how many fields will be written.