Class BlockTreeTermsReader

A block-based terms index and dictionary that assigns terms to variable length blocks according to how they share prefixes. The terms index is a prefix trie whose leaves are term blocks. The advantage of this approach is that SeekExact() is often able to determine a term cannot exist without doing any IO, and intersection with Automata is very fast. Note that this terms dictionary has it's own fixed terms index (ie, it does not support a pluggable terms index implementation).

NOTE: this terms dictionary does not support index divisor when opening an IndexReader. Instead, you can change the min/maxItemsPerBlock during indexing.

The data structure used by this implementation is very similar to a burst trie (http://citeseer.ist.psu.edu/viewdoc/summary?doi=10.1.1.18.3499), but with added logic to break up too-large blocks of all terms sharing a given prefix into smaller ones.

Use CheckIndex with the -verbose option to see summary statistics on the blocks in the dictionary.

See BlockTreeTermsWriter.

This is a Lucene.NET EXPERIMENTAL API, use at your own risk
Inheritance
System.Object
Fields
FieldsProducer
BlockTreeTermsReader
Implements
IDisposable
Inherited Members
Namespace: Lucene.Net.Codecs
Assembly: Lucene.Net.dll
Syntax
public class BlockTreeTermsReader : FieldsProducer, IDisposable

Constructors

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BlockTreeTermsReader(Directory, FieldInfos, SegmentInfo, PostingsReaderBase, IOContext, String, Int32)

Sole constructor.

Declaration
public BlockTreeTermsReader(Directory dir, FieldInfos fieldInfos, SegmentInfo info, PostingsReaderBase postingsReader, IOContext ioContext, string segmentSuffix, int indexDivisor)
Parameters
Type Name Description
Directory dir
FieldInfos fieldInfos
SegmentInfo info
PostingsReaderBase postingsReader
IOContext ioContext
System.String segmentSuffix
System.Int32 indexDivisor

Properties

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Count

Declaration
public override int Count { get; }
Property Value
Type Description
System.Int32
Overrides

Methods

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CheckIntegrity()

Declaration
public override void CheckIntegrity()
Overrides
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Dispose(Boolean)

Disposes all resources used by this object.

Declaration
protected override void Dispose(bool disposing)
Parameters
Type Name Description
System.Boolean disposing
Overrides
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GetEnumerator()

Declaration
public override IEnumerator<string> GetEnumerator()
Returns
Type Description
IEnumerator<System.String>
Overrides
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GetTerms(String)

Declaration
public override Terms GetTerms(string field)
Parameters
Type Name Description
System.String field
Returns
Type Description
Terms
Overrides
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RamBytesUsed()

Declaration
public override long RamBytesUsed()
Returns
Type Description
System.Int64
Overrides
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ReadHeader(IndexInput)

Reads terms file header.

Declaration
protected virtual int ReadHeader(IndexInput input)
Parameters
Type Name Description
IndexInput input
Returns
Type Description
System.Int32
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ReadIndexHeader(IndexInput)

Reads index file header.

Declaration
protected virtual int ReadIndexHeader(IndexInput input)
Parameters
Type Name Description
IndexInput input
Returns
Type Description
System.Int32
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SeekDir(IndexInput, Int64)

Seek input to the directory offset.

Declaration
protected virtual void SeekDir(IndexInput input, long dirOffset)
Parameters
Type Name Description
IndexInput input
System.Int64 dirOffset

Implements

IDisposable