Class CompactLabelToOrdinal

This is a very efficient LabelToOrdinal implementation that uses a Lucene.Net.Facet.Taxonomy.WriterCache.CharBlockArray to store all labels and a configurable number of Lucene.Net.Facet.Taxonomy.WriterCache.CompactLabelToOrdinal.HashArrays to reference the labels.

Since the Lucene.Net.Facet.Taxonomy.WriterCache.CompactLabelToOrdinal.HashArrays don't handle collisions, a CollisionMap is used to store the colliding labels.

This data structure grows by adding a new HashArray whenever the number of collisions in the CollisionMap exceeds Lucene.Net.Facet.Taxonomy.WriterCache.CompactLabelToOrdinal.loadFactor GetMaxOrdinal(). Growing also includes reinserting all colliding labels into the Lucene.Net.Facet.Taxonomy.WriterCache.CompactLabelToOrdinal.HashArrays to possibly reduce the number of collisions.

For setting the Lucene.Net.Facet.Taxonomy.WriterCache.CompactLabelToOrdinal.loadFactor see CompactLabelToOrdinal(Int32, Single, Int32).

This data structure has a much lower memory footprint (~30%) compared to a Java HashMap<String, Integer>. It also only uses a small fraction of objects a HashMap would use, thus limiting the GC overhead. Ingestion speed was also ~50% faster compared to a HashMap for 3M unique labels.

Note

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

Inheritance
System.Object
LabelToOrdinal
CompactLabelToOrdinal
Inherited Members
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)
System.Object.ToString()
Namespace: Lucene.Net.Facet.Taxonomy.WriterCache
Assembly: Lucene.Net.Facet.dll
Syntax
public class CompactLabelToOrdinal : LabelToOrdinal

Constructors

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CompactLabelToOrdinal(Int32, Single, Int32)

Sole constructor.

Declaration
public CompactLabelToOrdinal(int initialCapacity, float loadFactor, int numHashArrays)
Parameters
Type Name Description
System.Int32 initialCapacity
System.Single loadFactor
System.Int32 numHashArrays

Fields

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DefaultLoadFactor

Default maximum load factor.

Declaration
public const float DefaultLoadFactor = 0.15F
Field Value
Type Description
System.Single
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TERMINATOR_CHAR

Declaration
public const char TERMINATOR_CHAR = '\uffff'
Field Value
Type Description
System.Char

Properties

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SizeOfMap

How many labels.

Declaration
public virtual int SizeOfMap { get; }
Property Value
Type Description
System.Int32

Methods

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AddLabel(FacetLabel, Int32)

Declaration
public override void AddLabel(FacetLabel label, int ordinal)
Parameters
Type Name Description
FacetLabel label
System.Int32 ordinal
Overrides
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GetOrdinal(FacetLabel)

Declaration
public override int GetOrdinal(FacetLabel label)
Parameters
Type Name Description
FacetLabel label
Returns
Type Description
System.Int32
Overrides