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

Note

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

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()
Lucene.Net.Codecs.PostingsFormat.ForName(System.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

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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()
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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.
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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

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VERSION_CHECKSUM

Declaration
public static readonly int VERSION_CHECKSUM
Field Value
Type Description
System.Int32
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VERSION_CURRENT

Declaration
public static readonly int VERSION_CURRENT
Field Value
Type Description
System.Int32
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VERSION_START

Declaration
public static readonly int VERSION_START
Field Value
Type Description
System.Int32

Methods

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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)
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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)