org.apache.lucene.codecs.memory

Class MemoryPostingsFormat

java.lang.Object

org.apache.lucene.codecs.PostingsFormat

org.apache.lucene.codecs.memory.MemoryPostingsFormat

All Implemented Interfaces:

NamedSPILoader.NamedSPI

public final class MemoryPostingsFormat
extends PostingsFormat

Stores terms and postings (docs, positions, payloads) in RAM, using an FST.

Note that this codec implements advance as a linear scan! This means if you store large fields in here, queries that rely on advance will (AND BooleanQuery, PhraseQuery) will be relatively slow!

Field Summary

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

EMPTY

Constructor Summary

Constructors

Constructor and Description
MemoryPostingsFormat()
MemoryPostingsFormat(boolean doPackFST, float acceptableOverheadRatio) Create MemoryPostingsFormat, specifying advanced FST options.

Method Summary

Modifier and Type	Method and Description
FieldsConsumer	fieldsConsumer(SegmentWriteState state) Writes a new segment
FieldsProducer	fieldsProducer(SegmentReadState state) Reads a segment.
java.lang.String	toString()

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

availablePostingsFormats, forName, getName, reloadPostingsFormats

Methods inherited from class java.lang.Object

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

Constructor Detail

MemoryPostingsFormat

public MemoryPostingsFormat()

MemoryPostingsFormat

public MemoryPostingsFormat(boolean doPackFST,
                            float acceptableOverheadRatio)

Create MemoryPostingsFormat, specifying advanced FST options.

Parameters:

doPackFST - true if a packed FST should be built. NOTE: packed FSTs are limited to ~2.1 GB of postings.

acceptableOverheadRatio - allowable overhead for packed ints during FST construction.

Method Detail

toString

public java.lang.String toString()

Overrides:

toString in class PostingsFormat

fieldsConsumer

public FieldsConsumer fieldsConsumer(SegmentWriteState state)
                              throws java.io.IOException

Description copied from class: PostingsFormat

Writes a new segment

Specified by:

fieldsConsumer in class PostingsFormat

Throws:

java.io.IOException

fieldsProducer

public FieldsProducer fieldsProducer(SegmentReadState state)
                              throws java.io.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:

java.io.IOException