core/org.gnit.lucenekmp.index/SegmentInfos

SegmentInfos

class SegmentInfos(indexCreatedVersionMajor: Int) : Cloneable<SegmentInfos> , 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, ^SegCount, CommitUserData, Footer

Data types:

Header -->IndexHeader
LuceneVersion --> Which Lucene code Version was used for this commit, written as three DataOutput.writeVInt: major, minor, bugfix
MinSegmentLuceneVersion --> Lucene code Version of the oldest segment, written as three DataOutput.writeVInt: major, minor, bugfix; this is only written only if there's at least one segment
NameCounter, SegCount, DeletionCount -->DataOutput.writeInt
Generation, Version, DelGen, Checksum, FieldInfosGen, DocValuesGen -->DataOutput.writeLong
SegID -->DataOutput.writeByte
SegName, SegCodec -->DataOutput.writeString
CommitUserData -->DataOutput.writeMapOfStrings
UpdatesFiles --> Map
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 Codec.getName 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 that was passed to IndexWriter.setLiveCommitData.
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.

Constructors

SegmentInfos

constructor(indexCreatedVersionMajor: Int)

Types

Companion

object Companion

FindSegmentsFile

abstract class FindSegmentsFile<T>

Utility class for executing code that needs to do something with the current segments file. This is necessary with lock-less commits because from the time you locate the current segments file name, until you actually open it, read its contents, or check modified time, etc., it could have been deleted due to a writer commit finishing.

Properties

commitLuceneVersion

val commitLuceneVersion: Version?

counter

var counter: Long

Used to name new segments.

generation

var generation: Long

Returns current generation.

indexCreatedVersionMajor

val indexCreatedVersionMajor: Int

The Lucene version major that was used to create the index.

lastGeneration

var lastGeneration: Long

Returns last succesfully read or written generation.

pendingCommit

var pendingCommit: Boolean

segmentsFileName

val segmentsFileName: String?

userData

var userData: MutableMap<String, String>

Opaque Map that user can specify during IndexWriter.commit Return userData saved with this commit.

version

var version: Long

Functions

add

fun add(si: SegmentCommitInfo)

Appends the provided SegmentCommitInfo.

addAll

fun addAll(sis: Iterable<SegmentCommitInfo>)

Appends the provided SegmentCommitInfos.

applyMergeChanges

fun applyMergeChanges(merge: MergePolicy.OneMerge, dropSegment: Boolean)

applies all changes caused by committing a merge to this SegmentInfos

asList

fun asList(): MutableList<SegmentCommitInfo>

Returns all contained segments as an unmodifiable List view.

changed

fun changed()

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

clear

fun clear()

Clear all SegmentCommitInfos.

clone

open override fun clone(): SegmentInfos

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

commit

fun commit(dir: Directory)

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

contains

fun contains(si: SegmentCommitInfo): Boolean

Return true if the provided SegmentCommitInfo is contained.

createBackupSegmentInfos

fun createBackupSegmentInfos(): MutableList<SegmentCommitInfo>

files

fun files(includeSegmentsFile: Boolean): MutableCollection<String>

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

finishCommit

fun finishCommit(dir: Directory): String

Returns the committed segments_N filename.

getId

fun getId(): ByteArray

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

getMinSegmentLuceneVersion

fun getMinSegmentLuceneVersion(): Version?

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

indexOf

fun indexOf(si: SegmentCommitInfo): Int

Returns index of the provided SegmentCommitInfo.

info

fun info(i: Int): SegmentCommitInfo

Returns SegmentCommitInfo at the provided index.

iterator

open operator override fun iterator(): MutableIterator<SegmentCommitInfo>

Returns an unmodifiable Iterator of contained segments in order.

prepareCommit

fun prepareCommit(dir: Directory)

Call this to start a commit. This writes the new segments file, but writes an invalid checksum at the end, so that it is not visible to readers. Once this is called you must call .finishCommit to complete the commit or .rollbackCommit to abort it.

remove

fun remove(index: Int)

Remove the SegmentCommitInfo at the provided index.

fun remove(si: SegmentCommitInfo): Boolean

Remove the provided SegmentCommitInfo.

replace

fun replace(other: SegmentInfos)

Replaces all segments in this instance, but keeps generation, version, counter so that future commits remain write once.

rollbackCommit

fun rollbackCommit(dir: Directory)

rollbackSegmentInfos