SegmentInfos (Lucene 7.1.0 API)

java.lang.Object
- org.apache.lucene.index.SegmentInfos

All Implemented Interfaces:

Cloneable, Iterable<SegmentCommitInfo>
```
public final class SegmentInfos
extends Object
implements Cloneable, 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 --> Int8^ID_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.
WARNING: This API is experimental and might change in incompatible ways in the next release.

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
`int`	`counter` Used to name new segments.
`Map<String,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.

Constructor Summary

Constructors
Constructor and Description

SegmentInfos(int indexCreatedVersionMajor)
Sole constructor.

Constructors
Constructor and Description
`SegmentInfos(int indexCreatedVersionMajor)` Sole constructor.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`add(SegmentCommitInfo si)` Appends the provided `SegmentCommitInfo`.
`void`	`addAll(Iterable<SegmentCommitInfo> sis)` Appends the provided `SegmentCommitInfo`s.
`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 `SegmentCommitInfo`s.
`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
`Collection<String>`	`files(boolean includeSegmentsFile)` Returns all file names referenced by SegmentInfo.
`static long`	`generationFromSegmentsFileName(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 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(String[] files)` Get the generation of the most recent commit to the list of index files (N in the segments_N file).
`static String`	`getLastCommitSegmentsFileName(Directory directory)` Get the filename of the segments_N file for the most recent commit to the index in this Directory.
`static String`	`getLastCommitSegmentsFileName(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.
`String`	`getSegmentsFileName()` Get the segments_N filename in use by this segment infos.
`Map<String,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.
`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, String segmentFileName)` Read a particular segmentFileName.
`static SegmentInfos`	`readLatestCommit(Directory directory)` Find the latest commit (`segments_N file`) and load all `SegmentCommitInfo`s.
`void`	`remove(SegmentCommitInfo si)` Remove the provided `SegmentCommitInfo`.
`static void`	`setInfoStream(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(Map<String,String> data, boolean doIncrementVersion)` Sets the commit data.
`int`	`size()` Returns number of `SegmentCommitInfo`s.
`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
  - counter
```
public int counter
```
    Used to name new segments.
  - version
```
public long version
```
    Counts how often the index has been changed.
  - userData
```
public Map<String,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(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 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:
    
    IOException
  - getLastCommitSegmentsFileName
```
public static String getLastCommitSegmentsFileName(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 String getLastCommitSegmentsFileName(Directory directory)
                                            throws 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:
    
    IOException
  - getSegmentsFileName
```
public String getSegmentsFileName()
```
    Get the segments_N filename in use by this segment infos.
  - generationFromSegmentsFileName
```
public static long generationFromSegmentsFileName(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,
                                            String segmentFileName)
                                     throws 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
    
    IOException - if there is a low-level IO error
  - readCommit
```
public static final SegmentInfos readCommit(Directory directory,
                                            ChecksumIndexInput input,
                                            long generation)
                                     throws IOException
```
    Read the commit from the provided ChecksumIndexInput.
    
    Throws:
    
    IOException
  - readLatestCommit
```
public static final SegmentInfos readLatestCommit(Directory directory)
                                           throws IOException
```
    Find the latest commit (segments_N file) and load all SegmentCommitInfos.
    
    Throws:
    
    IOException
  - write
```
public void write(Directory directory,
                  IndexOutput out)
           throws IOException
```
    Write ourselves to the provided IndexOutput
    
    Throws:
    
    IOException
  - clone
```
public SegmentInfos clone()
```
    Returns a copy of this instance, also copying each SegmentInfo.
    
    Overrides:
    
    clone in class 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(PrintStream infoStream)
```
    If non-null, information about retries when loading the segments file will be printed to this.
  - getInfoStream
```
public static PrintStream getInfoStream()
```
    Returns infoStream.
    
    See Also:
    
    setInfoStream(java.io.PrintStream)
  - updateGeneration
```
public void updateGeneration(SegmentInfos other)
```
    Carry over generation numbers from another SegmentInfos
    
    NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.
  - setNextWriteGeneration
```
public void setNextWriteGeneration(long generation)
```
    Set the generation to be used for the next commit
  - files
```
public Collection<String> files(boolean includeSegmentsFile)
                         throws IOException
```
    Returns all file names referenced by SegmentInfo. The returned collection is recomputed on each invocation.
    
    Throws:
    
    IOException
  - commit
```
public final void commit(Directory dir)
                  throws 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:
    
    IOException
  - toString
```
public String toString()
```
    Returns readable description of this segment.
    
    Overrides:
    
    toString in class Object
  - getUserData
```
public Map<String,String> getUserData()
```
    Return userData saved with this commit.
    
    See Also:
    
    IndexWriter.commit()
  - setUserData
```
public void setUserData(Map<String,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 Iterator<SegmentCommitInfo> iterator()
```
    Returns an unmodifiable Iterator of contained segments in order.
    
    Specified by:
    
    iterator in interface Iterable<SegmentCommitInfo>
  - asList
```
public 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(Iterable<SegmentCommitInfo> sis)
```
    Appends the provided SegmentCommitInfos.
  - clear
```
public void clear()
```
    Clear all SegmentCommitInfos.
  - remove
```
public void 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.

Class SegmentInfos

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.lang.Iterable

Field Detail

VERSION_53

VERSION_70

counter

version

userData

Constructor Detail

SegmentInfos

Method Detail

info

getLastCommitGeneration

getLastCommitGeneration

getLastCommitSegmentsFileName

getLastCommitSegmentsFileName

getSegmentsFileName

generationFromSegmentsFileName

getId

readCommit

readCommit

readLatestCommit

write

clone

getVersion

getGeneration

getLastGeneration

setInfoStream

getInfoStream

updateGeneration

setNextWriteGeneration

files

commit

toString

getUserData

setUserData

totalMaxDoc

changed

iterator

asList

size

add

addAll

clear

remove

getCommitLuceneVersion

getMinSegmentLuceneVersion

getIndexCreatedVersionMajor