org.apache.lucene.index

Class SegmentInfos

java.lang.Object

org.apache.lucene.index.SegmentInfos

All Implemented Interfaces:

java.lang.Cloneable, java.lang.Iterable<SegmentCommitInfo>

public final class SegmentInfos
extends java.lang.Object
implements java.lang.Cloneable, java.lang.Iterable<SegmentCommitInfo>

A collection of segmentInfo objects with methods for operating on those segments in relation to the file system.

The active segments in the index are stored in the segment info file, segments_N. There may be one or more segments_N files in the index; however, the one with the largest generation is the active one (when older segments_N files are present it's because they temporarily cannot be deleted, or a custom IndexDeletionPolicy is in use). This file lists each segment by name and has details about the codec and generation of deletes.

Files:

• segments_N: Header, LuceneVersion, Version, NameCounter, SegCount, MinSegmentLuceneVersion, <SegName, SegID, SegCodec, DelGen, DeletionCount, FieldInfosGen, DocValuesGen, UpdatesFiles>^SegCount, CommitUserData, Footer

Data types:

• Header --> IndexHeader
• LuceneVersion --> Which Lucene code Version was used for this commit, written as three vInt: major, minor, bugfix
• MinSegmentLuceneVersion --> Lucene code Version of the oldest segment, written as three vInt: major, minor, bugfix; this is only written only if there's at least one segment
• NameCounter, SegCount, DeletionCount --> Int32
• Generation, Version, DelGen, Checksum, FieldInfosGen, DocValuesGen --> Int64
• SegID --> Int8ID_LENGTH
• SegName, SegCodec --> String
• CommitUserData --> Map<String,String>
• UpdatesFiles --> Map<Int32, Set<String>>
• Footer --> CodecFooter

Field Descriptions:

• Version counts how often the index has been changed by adding or deleting documents.
• NameCounter is used to generate names for new segment files.
• SegName is the name of the segment, and is used as the file name prefix for all of the files that compose the segment's index.
• DelGen is the generation count of the deletes file. If this is -1, there are no deletes. Anything above zero means there are deletes stored by LiveDocsFormat.
• DeletionCount records the number of deleted documents in this segment.
• SegCodec is the name of the Codec that encoded this segment.
• SegID is the identifier of the Codec that encoded this segment.
• CommitUserData stores an optional user-supplied opaque Map<String,String> that was passed to IndexWriter.setLiveCommitData(Iterable).
• FieldInfosGen is the generation count of the fieldInfos file. If this is -1, there are no updates to the fieldInfos in that segment. Anything above zero means there are updates to fieldInfos stored by FieldInfosFormat .
• DocValuesGen is the generation count of the updatable DocValues. If this is -1, there are no updates to DocValues in that segment. Anything above zero means there are updates to DocValues stored by DocValuesFormat.
• UpdatesFiles stores the set of files that were updated in that segment per field.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SegmentInfos.FindSegmentsFile<T> Utility class for executing code that needs to do something with the current segments file.

Field Summary

Fields

Modifier and Type	Field and Description
long	counter Used to name new segments.
java.util.Map<java.lang.String,java.lang.String>	userData Opaque Map<String, String> that user can specify during IndexWriter.commit
long	version Counts how often the index has been changed.
static int	VERSION_53 Adds the Version that committed this segments_N file, as well as the Version of the oldest segment, since 5.3+
static int	VERSION_70 The version that added information about the Lucene version at the time when the index has been created.
static int	VERSION_72 The version that updated segment name counter to be long instead of int.
static int	VERSION_74 The version that recorded softDelCount

Constructor Summary

Constructors

Constructor and Description
SegmentInfos(int indexCreatedVersionMajor) Sole constructor.

Method Summary

Modifier and Type	Method and Description
void	add(SegmentCommitInfo si) Appends the provided SegmentCommitInfo.
void	addAll(java.lang.Iterable<SegmentCommitInfo> sis) Appends the provided SegmentCommitInfos.
java.util.List<SegmentCommitInfo>	asList() Returns all contained segments as an unmodifiable List view.
void	changed() Call this before committing if changes have been made to the segments.
void	clear() Clear all SegmentCommitInfos.
SegmentInfos	clone() Returns a copy of this instance, also copying each SegmentInfo.
void	commit(Directory dir) Writes and syncs to the Directory dir, taking care to remove the segments file on exception
java.util.Collection<java.lang.String>	files(boolean includeSegmentsFile) Returns all file names referenced by SegmentInfo.
static long	generationFromSegmentsFileName(java.lang.String fileName) Parse the generation off the segments file name and return it.
Version	getCommitLuceneVersion() Returns which Lucene Version wrote this commit, or null if the version this index was written with did not directly record the version.
long	getGeneration() Returns current generation.
byte[]	getId() Since Lucene 5.0, every commit (segments_N) writes a unique id.
int	getIndexCreatedVersionMajor() Return the version major that was used to initially create the index.
static java.io.PrintStream	getInfoStream() Returns infoStream.
static long	getLastCommitGeneration(Directory directory) Get the generation of the most recent commit to the index in this directory (N in the segments_N file).
static long	getLastCommitGeneration(java.lang.String[] files) Get the generation of the most recent commit to the list of index files (N in the segments_N file).
static java.lang.String	getLastCommitSegmentsFileName(Directory directory) Get the filename of the segments_N file for the most recent commit to the index in this Directory.
static java.lang.String	getLastCommitSegmentsFileName(java.lang.String[] files) Get the filename of the segments_N file for the most recent commit in the list of index files.
long	getLastGeneration() Returns last succesfully read or written generation.
Version	getMinSegmentLuceneVersion() Returns the version of the oldest segment, or null if there are no segments.
java.lang.String	getSegmentsFileName() Get the segments_N filename in use by this segment infos.
java.util.Map<java.lang.String,java.lang.String>	getUserData() Return userData saved with this commit.
long	getVersion() version number when this SegmentInfos was generated.
SegmentCommitInfo	info(int i) Returns SegmentCommitInfo at the provided index.
java.util.Iterator<SegmentCommitInfo>	iterator() Returns an unmodifiable Iterator of contained segments in order.
static SegmentInfos	readCommit(Directory directory, ChecksumIndexInput input, long generation) Read the commit from the provided ChecksumIndexInput.
static SegmentInfos	readCommit(Directory directory, java.lang.String segmentFileName) Read a particular segmentFileName.
static SegmentInfos	readLatestCommit(Directory directory) Find the latest commit (segments_N file) and load all SegmentCommitInfos.
boolean	remove(SegmentCommitInfo si) Remove the provided SegmentCommitInfo.
static void	setInfoStream(java.io.PrintStream infoStream) If non-null, information about retries when loading the segments file will be printed to this.
void	setNextWriteGeneration(long generation) Set the generation to be used for the next commit
void	setUserData(java.util.Map<java.lang.String,java.lang.String> data, boolean doIncrementVersion) Sets the commit data.
int	size() Returns number of SegmentCommitInfos.
java.lang.String	toString() Returns readable description of this segment.
int	totalMaxDoc() Returns sum of all segment's maxDocs.
void	updateGeneration(SegmentInfos other) Carry over generation numbers from another SegmentInfos
void	write(Directory directory, IndexOutput out) Write ourselves to the provided IndexOutput

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

VERSION_53

public static final int VERSION_53

Adds the Version that committed this segments_N file, as well as the Version of the oldest segment, since 5.3+

See Also:

Constant Field Values

VERSION_70

public static final int VERSION_70

The version that added information about the Lucene version at the time when the index has been created.

See Also:

Constant Field Values

VERSION_72

public static final int VERSION_72

The version that updated segment name counter to be long instead of int.

See Also:

Constant Field Values

VERSION_74

public static final int VERSION_74

The version that recorded softDelCount

See Also:

Constant Field Values

counter

public long counter

Used to name new segments.

version

public long version

Counts how often the index has been changed.

userData

public java.util.Map<java.lang.String,java.lang.String> userData

Opaque Map<String, String> that user can specify during IndexWriter.commit

Constructor Detail

SegmentInfos

public SegmentInfos(int indexCreatedVersionMajor)

Sole constructor.

Parameters:

indexCreatedVersionMajor - the Lucene version major at index creation time, or 6 if the index was created before 7.0

Method Detail

info

public SegmentCommitInfo info(int i)

Returns SegmentCommitInfo at the provided index.

getLastCommitGeneration

public static long getLastCommitGeneration(java.lang.String[] files)

Get the generation of the most recent commit to the list of index files (N in the segments_N file).

Parameters:

files - -- array of file names to check

getLastCommitGeneration

public static long getLastCommitGeneration(Directory directory)
                                    throws java.io.IOException

Get the generation of the most recent commit to the index in this directory (N in the segments_N file).

Parameters:

directory - -- directory to search for the latest segments_N file

Throws:

java.io.IOException

getLastCommitSegmentsFileName

public static java.lang.String getLastCommitSegmentsFileName(java.lang.String[] files)

Get the filename of the segments_N file for the most recent commit in the list of index files.

Parameters:

files - -- array of file names to check

getLastCommitSegmentsFileName

public static java.lang.String getLastCommitSegmentsFileName(Directory directory)
                                                      throws java.io.IOException

Get the filename of the segments_N file for the most recent commit to the index in this Directory.

Parameters:

directory - -- directory to search for the latest segments_N file

Throws:

java.io.IOException

getSegmentsFileName

public java.lang.String getSegmentsFileName()

Get the segments_N filename in use by this segment infos.

generationFromSegmentsFileName

public static long generationFromSegmentsFileName(java.lang.String fileName)

Parse the generation off the segments file name and return it.

getId

public byte[] getId()

Since Lucene 5.0, every commit (segments_N) writes a unique id. This will return that id

readCommit

public static final SegmentInfos readCommit(Directory directory,
                                            java.lang.String segmentFileName)
                                     throws java.io.IOException

Read a particular segmentFileName. Note that this may throw an IOException if a commit is in process.

Parameters:

directory - -- directory containing the segments file

segmentFileName - -- segment file to load

Throws:

CorruptIndexException - if the index is corrupt

java.io.IOException - if there is a low-level IO error

readCommit

public static final SegmentInfos readCommit(Directory directory,
                                            ChecksumIndexInput input,
                                            long generation)
                                     throws java.io.IOException

Read the commit from the provided ChecksumIndexInput.

Throws:

java.io.IOException

readLatestCommit

public static final SegmentInfos readLatestCommit(Directory directory)
                                           throws java.io.IOException

Find the latest commit (segments_N file) and load all SegmentCommitInfos.

Throws:

java.io.IOException

write

public void write(Directory directory,
                  IndexOutput out)
           throws java.io.IOException

Write ourselves to the provided IndexOutput

Throws:

java.io.IOException

clone

public SegmentInfos clone()

Returns a copy of this instance, also copying each SegmentInfo.

Overrides:

clone in class java.lang.Object

getVersion

public long getVersion()

version number when this SegmentInfos was generated.

getGeneration

public long getGeneration()

Returns current generation.

getLastGeneration

public long getLastGeneration()

Returns last succesfully read or written generation.

setInfoStream

public static void setInfoStream(java.io.PrintStream infoStream)

If non-null, information about retries when loading the segments file will be printed to this.

getInfoStream

public static java.io.PrintStream getInfoStream()

Returns infoStream.

See Also:

setInfoStream(java.io.PrintStream)

updateGeneration

public void updateGeneration(SegmentInfos other)

Carry over generation numbers from another SegmentInfos

setNextWriteGeneration

public void setNextWriteGeneration(long generation)

Set the generation to be used for the next commit

files

public java.util.Collection<java.lang.String> files(boolean includeSegmentsFile)
                                             throws java.io.IOException

Returns all file names referenced by SegmentInfo. The returned collection is recomputed on each invocation.

Throws:

java.io.IOException

commit

public final void commit(Directory dir)
                  throws java.io.IOException

Writes and syncs to the Directory dir, taking care to remove the segments file on exception

Note: changed() should be called prior to this method if changes have been made to this SegmentInfos instance

Throws:

java.io.IOException

toString

public java.lang.String toString()

Returns readable description of this segment.

Overrides:

toString in class java.lang.Object

getUserData

public java.util.Map<java.lang.String,java.lang.String> getUserData()

Return userData saved with this commit.

See Also:

IndexWriter.commit()

setUserData

public void setUserData(java.util.Map<java.lang.String,java.lang.String> data,
                        boolean doIncrementVersion)

Sets the commit data.

totalMaxDoc

public int totalMaxDoc()

Returns sum of all segment's maxDocs. Note that this does not include deletions

changed

public void changed()

Call this before committing if changes have been made to the segments.

iterator

public java.util.Iterator<SegmentCommitInfo> iterator()

Returns an unmodifiable Iterator of contained segments in order.

Specified by:

iterator in interface java.lang.Iterable<SegmentCommitInfo>

asList

public java.util.List<SegmentCommitInfo> asList()

Returns all contained segments as an unmodifiable List view.

size

public int size()

Returns number of SegmentCommitInfos.

add

public void add(SegmentCommitInfo si)

Appends the provided SegmentCommitInfo.

addAll

public void addAll(java.lang.Iterable<SegmentCommitInfo> sis)

Appends the provided SegmentCommitInfos.

clear

public void clear()

Clear all SegmentCommitInfos.

remove

public boolean remove(SegmentCommitInfo si)

Remove the provided SegmentCommitInfo.

WARNING: O(N) cost

getCommitLuceneVersion

public Version getCommitLuceneVersion()

Returns which Lucene Version wrote this commit, or null if the version this index was written with did not directly record the version.

getMinSegmentLuceneVersion

public Version getMinSegmentLuceneVersion()

Returns the version of the oldest segment, or null if there are no segments.

getIndexCreatedVersionMajor

public int getIndexCreatedVersionMajor()

Return the version major that was used to initially create the index. This version is set when the index is first created and then never changes. This information was added as of version 7.0 so older indices report 6 as a creation version.