Package org.apache.lucene.codecs

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

See: Description

Class Summary

Class	Description
BlockTermsReader	Handles a terms dict, but decouples all details of doc/freqs/positions reading to an instance of PostingsReaderBase.
BlockTermState	Holds all state required for PostingsReaderBase to produce a DocsEnum without re-seeking the terms dict.
BlockTermsWriter	Writes terms dict, block-encoding (column stride) each term's metadata for each set of terms between two index terms.
BlockTreeTermsReader	A block-based terms index and dictionary that assigns terms to variable length blocks according to how they share prefixes.
BlockTreeTermsReader.Stats	BlockTree statistics for a single field returned by BlockTreeTermsReader.FieldReader.computeStats().
BlockTreeTermsWriter	block-based terms index and dictionary writer.
Codec	Encodes/decodes an inverted index segment.
CodecUtil	Utility class for reading and writing versioned headers.
DocValuesArraySource	DocValues DocValues.Source implementation backed by simple arrays.
DocValuesConsumer	Abstract API that consumes IndexableFields.
DocValuesFormat	Encodes/decodes DocValues
FieldInfosFormat	Encodes/decodes FieldInfos
FieldInfosReader	Codec API for reading FieldInfos.
FieldInfosWriter	Codec API for writing FieldInfos.
FieldsConsumer	Abstract API that consumes terms, doc, freq, prox, offset and payloads postings.
FieldsProducer	Abstract API that produces terms, doc, freq, prox and payloads postings.
FixedGapTermsIndexReader	TermsIndexReader for simple every-nth terms indexes.
FixedGapTermsIndexWriter	Selects every Nth term as and index term, and hold term bytes (mostly) fully expanded in memory.
LiveDocsFormat	Format for live/deleted documents
MappingMultiDocsAndPositionsEnum	Exposes flex API, merged from flex API of sub-segments, remapping docIDs (this is used for segment merging).
MappingMultiDocsEnum	Exposes flex API, merged from flex API of sub-segments, remapping docIDs (this is used for segment merging).
MultiLevelSkipListReader	This abstract class reads skip lists with multiple levels.
MultiLevelSkipListWriter	This abstract class writes skip lists with multiple levels.
NormsFormat	format for normalization factors
PerDocConsumer	Abstract API that consumes per document values.
PerDocProducer	Abstract API that provides access to one or more per-document storage features.
PerDocProducerBase	Abstract base class for PerDocProducer implementations
PostingsBaseFormat	Provides a PostingsReaderBase and PostingsWriterBase.
PostingsConsumer	Abstract API that consumes postings for an individual term.
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 DocsEnum and DocsAndPositionsEnum instances.
PostingsWriterBase	Extension of PostingsConsumer to support pluggable term dictionaries.
SegmentInfoFormat	Expert: Controls the format of the SegmentInfo (segment metadata file).
SegmentInfoReader	Specifies an API for classes that can read SegmentInfo information.
SegmentInfoWriter	Specifies an API for classes that can write out SegmentInfo data.
StoredFieldsFormat	Controls the format of stored fields
StoredFieldsReader	Codec API for reading stored fields: You need to implement StoredFieldsReader.visitDocument(int, StoredFieldVisitor) to read the stored fields for a document, implement StoredFieldsReader.clone() (creating clones of any IndexInputs used, etc), and Closeable.close()
StoredFieldsWriter	Codec API for writing stored fields:
TermsConsumer	Abstract API that consumes terms for an individual field.
TermsIndexReaderBase	BlockTermsReader interacts with an instance of this class to manage its terms index.
TermsIndexReaderBase.FieldIndexEnum	Similar to TermsEnum, except, the only "metadata" it reports for a given indexed term is the long fileOffset into the main terms dictionary file:
TermsIndexWriterBase	Base class for terms index implementations to plug into BlockTermsWriter.
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:
VariableGapTermsIndexReader	See VariableGapTermsIndexWriter
VariableGapTermsIndexWriter	Selects index terms according to provided pluggable VariableGapTermsIndexWriter.IndexTermSelector, and stores them in a prefix trie that's loaded entirely in RAM stored as an FST.
VariableGapTermsIndexWriter.EveryNOrDocFreqTermSelector	Sets an index term when docFreq >= docFreqThresh, or every interval terms.
VariableGapTermsIndexWriter.EveryNTermSelector	Same policy as FixedGapTermsIndexWriter
VariableGapTermsIndexWriter.IndexTermSelector	Hook for selecting which terms should be placed in the terms index.

Package org.apache.lucene.codecs Description

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
• FieldInfos - see FieldInfosFormat
• SegmentInfo - see SegmentInfoFormat
• Norms - see NormsFormat
• Live documents - see LiveDocsFormat

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 Lucene40Codec and override Lucene40Codec.getPostingsFormatForField(String) to return your custom postings format.