Class DocValuesFormat

Encodes/decodes per-document values.

Note, when extending this class, the name (Name) may written into the index in certain configurations. In order for the segment to be read, the name must resolve to your implementation via ForName(String). This method uses GetDocValuesFormat(String) to resolve format names.

To implement your own format:

  1. Subclass this class.
  2. Subclass DefaultDocValuesFormatFactory, override the Initialize() method, and add the line base.ScanForDocValuesFormats(typeof(YourDocValuesFormat).Assembly). If you have any format classes in your assembly that are not meant for reading, you can add the ExcludeDocValuesFormatFromScanAttribute to them so they are ignored by the scan.
  3. Set the new IDocValuesFormatFactory by calling SetDocValuesFormatFactory(IDocValuesFormatFactory) at application startup.
If your format has dependencies, you may also override GetDocValuesFormat(Type) to inject them via pure DI or a DI container. See DI-Friendly Framework to understand the approach used.

DocValuesFormat Names

Unlike the Java version, format names are by default convention-based on the class name. If you name your custom format class "MyCustomDocValuesFormat", the format name will the same name without the "DocValuesFormat" suffix: "MyCustom".

You can override this default behavior by using the DocValuesFormatNameAttribute to name the format differently than this convention. Format names must be all ASCII alphanumeric, and less than 128 characters in length.

Note

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

Inheritance
System.Object
DocValuesFormat
Lucene40DocValuesFormat
Lucene42DocValuesFormat
Lucene45DocValuesFormat
PerFieldDocValuesFormat
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)
Namespace: Lucene.Net.Codecs
Assembly: Lucene.Net.dll
Syntax
public abstract class DocValuesFormat

Constructors

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DocValuesFormat()

Creates a new docvalues format.

The provided name will be written into the index segment in some configurations (such as when using PerFieldDocValuesFormat): in such configurations, for the segment to be read this class should be registered by subclassing DefaultDocValuesFormatFactory and calling ScanForDocValuesFormats(Assembly) in the class constructor. The new IDocValuesFormatFactory can be registered by calling SetDocValuesFormatFactory(IDocValuesFormatFactory) at application startup.

Declaration
protected DocValuesFormat()

Properties

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AvailableDocValuesFormats

Returns a list of all available format names.

Declaration
public static ICollection<string> AvailableDocValuesFormats { get; }
Property Value
Type Description
System.Collections.Generic.ICollection<System.String>
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Name

Unique name that's used to retrieve this format when reading the index.

Declaration
public string Name { get; }
Property Value
Type Description
System.String

Methods

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FieldsConsumer(SegmentWriteState)

Returns a DocValuesConsumer to write docvalues to the index.

Declaration
public abstract DocValuesConsumer FieldsConsumer(SegmentWriteState state)
Parameters
Type Name Description
SegmentWriteState state
Returns
Type Description
DocValuesConsumer
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FieldsProducer(SegmentReadState)

Returns a DocValuesProducer to read docvalues from the index.

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 System.IO.IOException should be thrown by the implementation. System.IO.IOExceptions are expected and will automatically cause a retry of the segment opening logic with the newly revised segments.

Declaration
public abstract DocValuesProducer FieldsProducer(SegmentReadState state)
Parameters
Type Name Description
SegmentReadState state
Returns
Type Description
DocValuesProducer
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ForName(String)

Looks up a format by name.

Declaration
public static DocValuesFormat ForName(string name)
Parameters
Type Name Description
System.String name
Returns
Type Description
DocValuesFormat
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GetDocValuesFormatFactory()

Gets the associated DocValuesFormat factory.

Declaration
public static IDocValuesFormatFactory GetDocValuesFormatFactory()
Returns
Type Description
IDocValuesFormatFactory

The DocValuesFormat factory.
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SetDocValuesFormatFactory(IDocValuesFormatFactory)

Sets the IDocValuesFormatFactory instance used to instantiate DocValuesFormat subclasses.

Declaration
public static void SetDocValuesFormatFactory(IDocValuesFormatFactory docValuesFormatFactory)
Parameters
Type Name Description
IDocValuesFormatFactory docValuesFormatFactory

The new IDocValuesFormatFactory.
Exceptions
Type Condition
System.ArgumentNullException

The docValuesFormatFactory parameter is null.
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ToString()

Declaration
public override string ToString()
Returns
Type Description
System.String
Overrides
System.Object.ToString()

See Also