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, int))
• DelegatePostingsFormatName --> String (WriteString(string)) The name of a ServiceProvider registered Lucene.Net.Codecs.PostingsFormat
• NumFilteredFields --> Uint32 (WriteInt32(int))
• FieldNumber --> Uint32 (WriteInt32(int)) 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

object

PostingsFormat

BloomFilteringPostingsFormat

Inherited Members

PostingsFormat.EMPTY

PostingsFormat.SetPostingsFormatFactory(IPostingsFormatFactory)

PostingsFormat.GetPostingsFormatFactory()

PostingsFormat.Name

PostingsFormat.ToString()

PostingsFormat.ForName(string)

PostingsFormat.AvailablePostingsFormats

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, 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
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
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

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, int))
• DelegatePostingsFormatName --> String (WriteString(string)) The name of a ServiceProvider registered Lucene.Net.Codecs.PostingsFormat
• NumFilteredFields --> Uint32 (WriteInt32(int))
• FieldNumber --> Uint32 (WriteInt32(int)) 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.

Declaration

public static readonly int VERSION_CHECKSUM

Field Value

Type	Description
int

VERSION_CURRENT

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, int))
• DelegatePostingsFormatName --> String (WriteString(string)) The name of a ServiceProvider registered Lucene.Net.Codecs.PostingsFormat
• NumFilteredFields --> Uint32 (WriteInt32(int))
• FieldNumber --> Uint32 (WriteInt32(int)) 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.

Declaration

public static readonly int VERSION_CURRENT

Field Value

Type	Description
int

VERSION_START

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, int))
• DelegatePostingsFormatName --> String (WriteString(string)) The name of a ServiceProvider registered Lucene.Net.Codecs.PostingsFormat
• NumFilteredFields --> Uint32 (WriteInt32(int))
• FieldNumber --> Uint32 (WriteInt32(int)) 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.

Declaration

public static readonly int VERSION_START

Field Value

Type	Description
int

Methods

FieldsConsumer(SegmentWriteState)

Writes a new segment.

Declaration

public override FieldsConsumer FieldsConsumer(SegmentWriteState state)

Parameters

Type	Name	Description
SegmentWriteState	state

Returns

Type	Description
FieldsConsumer

Overrides

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

FieldsProducer(SegmentReadState)

Reads a segment. NOTE: by the time this call returns, it must hold open any files it will need to use; else, those files may be deleted. Additionally, required files may be deleted during the execution of this call before there is a chance to open them. Under these circumstances an IOException should be thrown by the implementation. IOExceptions are expected and will automatically cause a retry of the segment opening logic with the newly revised segments.

Declaration

public override FieldsProducer FieldsProducer(SegmentReadState state)

Parameters

Type	Name	Description
SegmentReadState	state

Returns

Type	Description
FieldsProducer

Overrides

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