Class BloomFilteringPostingsFormat

A Lucene.Net.Codecs.PostingsFormat useful for low doc-frequency fields such as primary keys. Bloom filters are maintained in a ".blm" file which offers "fast-fail" for reads in segments known to have no record of the key. A choice of delegate Lucene.Net.Codecs.PostingsFormat is used to record all other Postings data.

A choice of BloomFilterFactory can be passed to tailor Bloom Filter settings on a per-field basis. The default configuration is DefaultBloomFilterFactory which allocates a ~8mb bitset and hashes values using MurmurHash2. This should be suitable for most purposes.

The format of the blm file is as follows:

• BloomFilter (.blm) --> Header, DelegatePostingsFormatName, NumFilteredFields, Filter^{NumFilteredFields}, Footer
• Filter --> FieldNumber, FuzzySet
• FuzzySet -->See Serialize(DataOutput)
• Header --> CodecHeader (WriteHeader(DataOutput, String, Int32))
• DelegatePostingsFormatName --> String (WriteString(String)) The name of a ServiceProvider registered Lucene.Net.Codecs.PostingsFormat
• NumFilteredFields --> Uint32 (WriteInt32(Int32))
• FieldNumber --> Uint32 (WriteInt32(Int32)) The number of the field in this segment
• Footer --> CodecFooter (WriteFooter(IndexOutput))

This is a Lucene.NET EXPERIMENTAL API, use at your own risk

Inheritance

System.Object

Lucene.Net.Codecs.PostingsFormat

BloomFilteringPostingsFormat

Inherited Members

Lucene.Net.Codecs.PostingsFormat.EMPTY

Lucene.Net.Codecs.PostingsFormat.SetPostingsFormatFactory(Lucene.Net.Codecs.IPostingsFormatFactory)

Lucene.Net.Codecs.PostingsFormat.GetPostingsFormatFactory()

Lucene.Net.Codecs.PostingsFormat.Name

Lucene.Net.Codecs.PostingsFormat.ToString()

PostingsFormat.ForName(String)

Lucene.Net.Codecs.PostingsFormat.AvailablePostingsFormats

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

System.Object.ReferenceEquals(System.Object, System.Object)

Namespace: Lucene.Net.Codecs.Bloom

Assembly: Lucene.Net.Codecs.dll

Syntax

[PostingsFormatName("BloomFilter")]
public sealed class BloomFilteringPostingsFormat : PostingsFormat

Constructors

BloomFilteringPostingsFormat()

Used only by core Lucene at read-time via Service Provider instantiation - do not use at Write-time in application code.

Declaration

public BloomFilteringPostingsFormat()

BloomFilteringPostingsFormat(PostingsFormat)

Creates Bloom filters for a selection of fields created in the index. This is recorded as a set of Bitsets held as a segment summary in an additional "blm" file. This Lucene.Net.Codecs.PostingsFormat delegates to a choice of delegate Lucene.Net.Codecs.PostingsFormat for encoding all other postings data. This choice of constructor defaults to the DefaultBloomFilterFactory for configuring per-field BloomFilters.

Declaration

public BloomFilteringPostingsFormat(PostingsFormat delegatePostingsFormat)

Parameters

Type	Name	Description
Lucene.Net.Codecs.PostingsFormat	delegatePostingsFormat	The Lucene.Net.Codecs.PostingsFormat that records all the non-bloom filter data i.e. postings info.

BloomFilteringPostingsFormat(PostingsFormat, BloomFilterFactory)

Creates Bloom filters for a selection of fields created in the index. This is recorded as a set of Bitsets held as a segment summary in an additional "blm" file. This Lucene.Net.Codecs.PostingsFormat delegates to a choice of delegate Lucene.Net.Codecs.PostingsFormat for encoding all other postings data.

Declaration

public BloomFilteringPostingsFormat(PostingsFormat delegatePostingsFormat, BloomFilterFactory bloomFilterFactory)

Parameters

Type	Name	Description
Lucene.Net.Codecs.PostingsFormat	delegatePostingsFormat	The Lucene.Net.Codecs.PostingsFormat that records all the non-bloom filter data i.e. postings info.
BloomFilterFactory	bloomFilterFactory	The BloomFilterFactory responsible for sizing BloomFilters appropriately.

Fields

VERSION_CHECKSUM

Declaration

public static readonly int VERSION_CHECKSUM

Field Value

Type	Description
System.Int32

VERSION_CURRENT

Declaration

public static readonly int VERSION_CURRENT

Field Value

Type	Description
System.Int32

VERSION_START

Declaration

public static readonly int VERSION_START

Field Value

Type	Description
System.Int32

Methods

FieldsConsumer(SegmentWriteState)

Declaration

public override FieldsConsumer FieldsConsumer(SegmentWriteState state)

Parameters

Type	Name	Description
Lucene.Net.Index.SegmentWriteState	state

Returns

Type	Description
Lucene.Net.Codecs.FieldsConsumer

Overrides

Lucene.Net.Codecs.PostingsFormat.FieldsConsumer(Lucene.Net.Index.SegmentWriteState)

FieldsProducer(SegmentReadState)

Declaration

public override FieldsProducer FieldsProducer(SegmentReadState state)

Parameters

Type	Name	Description
Lucene.Net.Index.SegmentReadState	state

Returns

Type	Description
Lucene.Net.Codecs.FieldsProducer

Overrides

Lucene.Net.Codecs.PostingsFormat.FieldsProducer(Lucene.Net.Index.SegmentReadState)