Package org.apache.lucene.codecs.perfield

Class PerFieldPostingsFormat

java.lang.Object

org.apache.lucene.codecs.PostingsFormat

org.apache.lucene.codecs.perfield.PerFieldPostingsFormat

All Implemented Interfaces:

NamedSPILoader.NamedSPI

public abstract class PerFieldPostingsFormat
extends PostingsFormat

Enables per field postings support.

Note, when extending this class, the name (PostingsFormat.getName()) is written into the index. In order for the field to be read, the name must resolve to your implementation via PostingsFormat.forName(String). This method uses Java's Service Provider Interface to resolve format names.

Files written by each posting format have an additional suffix containing the format name. For example, in a per-field configuration instead of _1.prx filenames would look like _1_Lucene40_0.prx.

See Also:

• ServiceLoader

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

Field Summary

Fields

Modifier and Type	Field	Description
static final String	PER_FIELD_FORMAT_KEY	FieldInfo attribute name used to store the format name for each field.
static final String	PER_FIELD_NAME	Name of this PostingsFormat.
static final String	PER_FIELD_SUFFIX_KEY	FieldInfo attribute name used to store the segment suffix name for each field.

Fields inherited from class org.apache.lucene.codecs.PostingsFormat

EMPTY

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	PerFieldPostingsFormat()	Sole constructor.

Method Summary

Modifier and Type	Method	Description
final FieldsConsumer	fieldsConsumer(SegmentWriteState state)	Writes a new segment
final FieldsProducer	fieldsProducer(SegmentReadState state)	Reads a segment.
abstract PostingsFormat	getPostingsFormatForField(String field)	Returns the postings format that should be used for writing new segments of field.

Methods inherited from class org.apache.lucene.codecs.PostingsFormat

availablePostingsFormats, forName, getName, reloadPostingsFormats, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

PER_FIELD_NAME

public static final String PER_FIELD_NAME

Name of this PostingsFormat.

See Also:

• Constant Field Values

PER_FIELD_FORMAT_KEY

public static final String PER_FIELD_FORMAT_KEY

FieldInfo attribute name used to store the format name for each field.

PER_FIELD_SUFFIX_KEY

public static final String PER_FIELD_SUFFIX_KEY

FieldInfo attribute name used to store the segment suffix name for each field.

Constructor Details

PerFieldPostingsFormat

protected PerFieldPostingsFormat()

Sole constructor.

Method Details

fieldsConsumer

public final FieldsConsumer fieldsConsumer(SegmentWriteState state)
                                    throws IOException

Description copied from class: PostingsFormat

Writes a new segment

Specified by:

fieldsConsumer in class PostingsFormat

Throws:

IOException

fieldsProducer

public final FieldsProducer fieldsProducer(SegmentReadState state)
                                    throws IOException

Description copied from class: PostingsFormat

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.

Specified by:

fieldsProducer in class PostingsFormat

Throws:

IOException

getPostingsFormatForField

public abstract PostingsFormat getPostingsFormatForField(String field)

Returns the postings format that should be used for writing new segments of field.

The field to format mapping is written to the index, so this method is only invoked when writing, not when reading.