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.

@lucene.experimental

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