LiveIndexWriterConfig (Lucene 10.5.1 core API)
Description: declaration: package: org.apache.lucene.index, class: LiveIndexWriterConfig

Package org.apache.lucene.index

# Class LiveIndexWriterConfig

java.lang.Object
org.apache.lucene.index.LiveIndexWriterConfig

Direct Known Subclasses:
  `IndexWriterConfig`

public class LiveIndexWriterConfig extends Object
Holds all the configuration used by `IndexWriter` with few setters for settings that can be changed on an `IndexWriter` instance "live".

Since:
  4.0

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected boolean`
  `checkPendingFlushOnUpdate`
  if an indexing thread should check for pending flushes on update in order to help out on a full flush
  `protected Codec`
  `codec`
  `Codec` used to write new segments.
  `protected IndexCommit`
  `commit`
  `IndexCommit` that `IndexWriter` is opened on.
  `protected boolean`
  `commitOnClose`
  True if calls to `IndexWriter.close()` should first do a commit.
  `protected int`
  `createdVersionMajor`
  Compatibility version to use for this index.
  `protected IndexDeletionPolicy`
  `delPolicy`
  `IndexDeletionPolicy` controlling when commit points are deleted.
  `protected IndexWriterEventListener`
  `eventListener`
  The IndexWriter event listener to record key events *
  `protected org.apache.lucene.index.FlushPolicy`
  `flushPolicy`
  `FlushPolicy` to control when segments are flushed.
  `protected Sort`
  `indexSort`
  The sort order to use to write merged segments.
  `protected Set<String>`
  `indexSortFields`
  The field names involved in the index sort
  `protected InfoStream`
  `infoStream`
  `InfoStream` for debugging messages.
  `protected Comparator<LeafReader>`
  `leafSorter`
  The comparator for sorting leaf readers.
  `protected long`
  `maxFullFlushMergeWaitMillis`
  Amount of time to wait for merges returned by MergePolicy.findFullFlushMerges(...)
  `protected MergePolicy`
  `mergePolicy`
  `MergePolicy` for selecting merges.
  `protected MergeScheduler`
  `mergeScheduler`
  `MergeScheduler` to use for running merges.
  `protected IndexWriterConfig.OpenMode`
  `openMode`
  `IndexWriterConfig.OpenMode` that `IndexWriter` is opened with.
  `protected String`
  `parentField`
  parent document field
  `protected int`
  `perThreadHardLimitMB`
  Sets the hard upper bound on RAM usage for a single segment, after which the segment is forced to flush.
  `protected boolean`
  `readerPooling`
  True if readers should be pooled.
  `protected Similarity`
  `similarity`
  `Similarity` to use when encoding norms.
  `protected String`
  `softDeletesField`
  soft deletes field
  `protected boolean`
  `useCompoundFile`
  True if segment flushes should use compound file format

- ## Method Summary

  Modifier and Type
  Method
  Description
  `Analyzer`
  `getAnalyzer()`
  Returns the default analyzer to use for indexing documents.
  `Codec`
  `getCodec()`
  Returns the current `Codec`.
  `boolean`
  `getCommitOnClose()`
  Returns `true` if `IndexWriter.close()` should first commit before closing.
  `IndexCommit`
  `getIndexCommit()`
  Returns the `IndexCommit` as specified in `IndexWriterConfig.setIndexCommit(IndexCommit)` or the default, `null` which specifies to open the latest index commit point.
  `int`
  `getIndexCreatedVersionMajor()`
  Return the compatibility version to use for this index.
  `IndexDeletionPolicy`
  `getIndexDeletionPolicy()`
  Returns the `IndexDeletionPolicy` specified in `IndexWriterConfig.setIndexDeletionPolicy(IndexDeletionPolicy)` or the default `KeepOnlyLastCommitDeletionPolicy`/
  `Sort`
  `getIndexSort()`
  Get the index-time `Sort` order, applied to all (flushed and merged) segments.
  `Set<String>`
  `getIndexSortFields()`
  Returns the field names involved in the index sort
  `IndexWriterEventListener`
  `getIndexWriterEventListener()`
  Returns the IndexWriterEventListener callback that tracks the key IndexWriter operations.
  `InfoStream`
  `getInfoStream()`
  Returns `InfoStream` used for debugging.
  `Comparator<LeafReader>`
  `getLeafSorter()`
  Returns a comparator for sorting leaf readers.
  `int`
  `getMaxBufferedDocs()`
  Returns the number of buffered added documents that will trigger a flush if enabled.
  `long`
  `getMaxFullFlushMergeWaitMillis()`
  Expert: return the amount of time to wait for merges returned by by MergePolicy.findFullFlushMerges(...).
  `IndexWriter.IndexReaderWarmer`
  `getMergedSegmentWarmer()`
  Returns the current merged segment warmer.
  `MergePolicy`
  `getMergePolicy()`
  Returns the current MergePolicy in use by this writer.
  `MergeScheduler`
  `getMergeScheduler()`
  Returns the `MergeScheduler` that was set by `IndexWriterConfig.setMergeScheduler(MergeScheduler)`.
  `IndexWriterConfig.OpenMode`
  `getOpenMode()`
  Returns the `IndexWriterConfig.OpenMode` set by `IndexWriterConfig.setOpenMode(OpenMode)`.
  `String`
  `getParentField()`
  Returns the parent document field name if configured.
  `double`
  `getRAMBufferSizeMB()`
  Returns the value set by `setRAMBufferSizeMB(double)` if enabled.
  `int`
  `getRAMPerThreadHardLimitMB()`
  Returns the max amount of memory each `DocumentsWriterPerThread` can consume until forcefully flushed.
  `boolean`
  `getReaderPooling()`
  Returns `true` if `IndexWriter` should pool readers even if `DirectoryReader.open(IndexWriter)` has not been called.
  `Similarity`
  `getSimilarity()`
  Expert: returns the `Similarity` implementation used by this `IndexWriter`.
  `String`
  `getSoftDeletesField()`
  Returns the soft deletes field or `null` if soft-deletes are disabled.
  `boolean`
  `getUseCompoundFile()`
  Returns `true` iff the `IndexWriter` packs newly written segments in a compound file.
  `boolean`
  `isCheckPendingFlushOnUpdate()`
  Expert: Returns if indexing threads check for pending flushes on update in order to help our flushing indexing buffers to disk
  `LiveIndexWriterConfig`
  `setCheckPendingFlushUpdate(boolean checkPendingFlushOnUpdate)`
  Expert: sets if indexing threads check for pending flushes on update in order to help our flushing indexing buffers to disk.
  `LiveIndexWriterConfig`
  `setMaxBufferedDocs(int maxBufferedDocs)`
  Determines the minimal number of documents required before the buffered in-memory documents are flushed as a new Segment.
  `LiveIndexWriterConfig`
  `setMergedSegmentWarmer(IndexWriter.IndexReaderWarmer mergeSegmentWarmer)`
  Set the merged segment warmer.
  `LiveIndexWriterConfig`
  `setMergePolicy(MergePolicy mergePolicy)`
  Expert: `MergePolicy` is invoked whenever there are changes to the segments in the index.
  `LiveIndexWriterConfig`
  `setRAMBufferSizeMB(double ramBufferSizeMB)`
  Determines the amount of RAM that may be used for buffering added documents and deletions before they are flushed to the Directory.
  `LiveIndexWriterConfig`
  `setUseCompoundFile(boolean useCompoundFile)`
  Sets if the `IndexWriter` should pack newly written segments in a compound file.
  `String`
  `toString()`

  ### Methods inherited from class java.lang.Object

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

- ## Field Details

  - ### delPolicy

    protected volatile IndexDeletionPolicy delPolicy
    `IndexDeletionPolicy` controlling when commit points are deleted.

  - ### commit

    protected volatile IndexCommit commit
    `IndexCommit` that `IndexWriter` is opened on.

  - ### openMode

    protected volatile IndexWriterConfig.OpenMode openMode
    `IndexWriterConfig.OpenMode` that `IndexWriter` is opened with.

  - ### createdVersionMajor

    protected int createdVersionMajor
    Compatibility version to use for this index.

  - ### similarity

    protected volatile Similarity similarity
    `Similarity` to use when encoding norms.

  - ### mergeScheduler

    protected volatile MergeScheduler mergeScheduler
    `MergeScheduler` to use for running merges.

  - ### codec

    protected volatile Codec codec
    `Codec` used to write new segments.

  - ### infoStream

    protected volatile InfoStream infoStream
    `InfoStream` for debugging messages.

  - ### mergePolicy

    protected volatile MergePolicy mergePolicy
    `MergePolicy` for selecting merges.

  - ### readerPooling

    protected volatile boolean readerPooling
    True if readers should be pooled.

  - ### flushPolicy

    protected volatile org.apache.lucene.index.FlushPolicy flushPolicy
    `FlushPolicy` to control when segments are flushed.

  - ### perThreadHardLimitMB

    protected volatile int perThreadHardLimitMB
    Sets the hard upper bound on RAM usage for a single segment, after which the segment is forced to flush.

  - ### useCompoundFile

    protected volatile boolean useCompoundFile
    True if segment flushes should use compound file format

  - ### commitOnClose

    protected boolean commitOnClose
    True if calls to `IndexWriter.close()` should first do a commit.

  - ### indexSort

    protected Sort indexSort
    The sort order to use to write merged segments.

  - ### leafSorter

    protected Comparator<LeafReader> leafSorter
    The comparator for sorting leaf readers.

  - ### indexSortFields

    protected Set<String> indexSortFields
    The field names involved in the index sort

  - ### parentField

    protected String parentField
    parent document field

  - ### checkPendingFlushOnUpdate

    protected volatile boolean checkPendingFlushOnUpdate
    if an indexing thread should check for pending flushes on update in order to help out on a full flush

  - ### softDeletesField

    protected String softDeletesField
    soft deletes field

  - ### maxFullFlushMergeWaitMillis

    protected volatile long maxFullFlushMergeWaitMillis
    Amount of time to wait for merges returned by MergePolicy.findFullFlushMerges(...)

  - ### eventListener

    protected IndexWriterEventListener eventListener
    The IndexWriter event listener to record key events *

- ## Method Details

  - ### getAnalyzer

    public Analyzer getAnalyzer()
    Returns the default analyzer to use for indexing documents.

  - ### setRAMBufferSizeMB

    public LiveIndexWriterConfig setRAMBufferSizeMB(double ramBufferSizeMB)
    Determines the amount of RAM that may be used for buffering added documents and deletions before they are flushed to the Directory. Generally for faster indexing performance it's best to flush by RAM usage instead of document count and use as large a RAM buffer as you can.

    When this is set, the writer will flush whenever buffered documents and deletions use this much RAM. Pass in `IndexWriterConfig.DISABLE_AUTO_FLUSH` to prevent triggering a flush due to RAM usage. Note that if flushing by document count is also enabled, then the flush will be triggered by whichever comes first.

    The maximum RAM limit is inherently determined by the JVMs available memory. Yet, an `IndexWriter` session can consume a significantly larger amount of memory than the given RAM limit since this limit is just an indicator when to flush memory resident documents to the Directory. Flushes are likely happen concurrently while other threads adding documents to the writer. For application stability the available memory in the JVM should be significantly larger than the RAM buffer used for indexing.

    NOTE: the account of RAM usage for pending deletions is only approximate. Specifically, if you delete by Query, Lucene currently has no way to measure the RAM usage of individual Queries so the accounting will under-estimate and you should compensate by either calling commit() or refresh() periodically yourself.

    NOTE: It's not guaranteed that all memory resident documents are flushed once this limit is exceeded. Depending on the configured `FlushPolicy` only a subset of the buffered documents are flushed and therefore only parts of the RAM buffer is released.

    The default value is `IndexWriterConfig.DEFAULT_RAM_BUFFER_SIZE_MB`.

    Takes effect immediately, but only the next time a document is added, updated or deleted.

    Throws:
      `IllegalArgumentException` - if ramBufferSize is enabled but non-positive, or it disables ramBufferSize when maxBufferedDocs is already disabled
    See Also:
      - `IndexWriterConfig.setRAMPerThreadHardLimitMB(int)`

  - ### getRAMBufferSizeMB

    public double getRAMBufferSizeMB()
    Returns the value set by `setRAMBufferSizeMB(double)` if enabled.

  - ### setMaxBufferedDocs

    public LiveIndexWriterConfig setMaxBufferedDocs(int maxBufferedDocs)
    Determines the minimal number of documents required before the buffered in-memory documents are flushed as a new Segment. Large values generally give faster indexing.

    When this is set, the writer will flush every maxBufferedDocs added documents. Pass in `IndexWriterConfig.DISABLE_AUTO_FLUSH` to prevent triggering a flush due to number of buffered documents. Note that if flushing by RAM usage is also enabled, then the flush will be triggered by whichever comes first.

    Disabled by default (writer flushes by RAM usage).

    Takes effect immediately, but only the next time a document is added, updated or deleted.

    Throws:
      `IllegalArgumentException` - if maxBufferedDocs is enabled but smaller than 2, or it disables maxBufferedDocs when ramBufferSize is already disabled
    See Also:
      - `setRAMBufferSizeMB(double)`

  - ### getMaxBufferedDocs

    public int getMaxBufferedDocs()
    Returns the number of buffered added documents that will trigger a flush if enabled.
    See Also:
      - `setMaxBufferedDocs(int)`

  - ### setMergePolicy

    public LiveIndexWriterConfig setMergePolicy(MergePolicy mergePolicy)
    Expert: `MergePolicy` is invoked whenever there are changes to the segments in the index. Its role is to select which merges to do, if any, and return a `MergePolicy.MergeSpecification` describing the merges. It also selects merges to do for forceMerge.

    Takes effect on subsequent merge selections. Any merges in flight or any merges already registered by the previous `MergePolicy` are not affected.

  - ### setMergedSegmentWarmer

    public LiveIndexWriterConfig setMergedSegmentWarmer(IndexWriter.IndexReaderWarmer mergeSegmentWarmer)
    Set the merged segment warmer. See `IndexWriter.IndexReaderWarmer`.

    Takes effect on the next merge.

  - ### getMergedSegmentWarmer

    public IndexWriter.IndexReaderWarmer getMergedSegmentWarmer()
    Returns the current merged segment warmer. See `IndexWriter.IndexReaderWarmer`.

  - ### getOpenMode

    public IndexWriterConfig.OpenMode getOpenMode()
    Returns the `IndexWriterConfig.OpenMode` set by `IndexWriterConfig.setOpenMode(OpenMode)`.

  - ### getIndexCreatedVersionMajor

    public int getIndexCreatedVersionMajor()
    Return the compatibility version to use for this index.
    See Also:
      - `IndexWriterConfig.setIndexCreatedVersionMajor(int)`

  - ### getIndexDeletionPolicy

    public IndexDeletionPolicy getIndexDeletionPolicy()
    Returns the `IndexDeletionPolicy` specified in `IndexWriterConfig.setIndexDeletionPolicy(IndexDeletionPolicy)` or the default `KeepOnlyLastCommitDeletionPolicy`/

  - ### getIndexCommit

    public IndexCommit getIndexCommit()
    Returns the `IndexCommit` as specified in `IndexWriterConfig.setIndexCommit(IndexCommit)` or the default, `null` which specifies to open the latest index commit point.

  - ### getSimilarity

    public Similarity getSimilarity()
    Expert: returns the `Similarity` implementation used by this `IndexWriter`.

  - ### getMergeScheduler

    public MergeScheduler getMergeScheduler()
    Returns the `MergeScheduler` that was set by `IndexWriterConfig.setMergeScheduler(MergeScheduler)`.

  - ### getCodec

    public Codec getCodec()
    Returns the current `Codec`.

  - ### getMergePolicy

    public MergePolicy getMergePolicy()
    Returns the current MergePolicy in use by this writer.
    See Also:
      - `IndexWriterConfig.setMergePolicy(MergePolicy)`

  - ### getReaderPooling

    public boolean getReaderPooling()
    Returns `true` if `IndexWriter` should pool readers even if `DirectoryReader.open(IndexWriter)` has not been called.

  - ### getRAMPerThreadHardLimitMB

    public int getRAMPerThreadHardLimitMB()
    Returns the max amount of memory each `DocumentsWriterPerThread` can consume until forcefully flushed.
    See Also:
      - `IndexWriterConfig.setRAMPerThreadHardLimitMB(int)`

  - ### getInfoStream

    public InfoStream getInfoStream()
    Returns `InfoStream` used for debugging.
    See Also:
      - `IndexWriterConfig.setInfoStream(InfoStream)`

  - ### setUseCompoundFile

    public LiveIndexWriterConfig setUseCompoundFile(boolean useCompoundFile)
    Sets if the `IndexWriter` should pack newly written segments in a compound file. Default is `true`.

    Use `false` for batch indexing with very large ram buffer settings.

    Note: To control compound file usage during segment merges see `MergePolicy.setNoCFSRatio(double)` and `MergePolicy.setMaxCFSSegmentSizeMB(double)`. This setting only applies to newly created segments.

  - ### getUseCompoundFile

    public boolean getUseCompoundFile()
    Returns `true` iff the `IndexWriter` packs newly written segments in a compound file. Default is `true`.

  - ### getCommitOnClose

    public boolean getCommitOnClose()
    Returns `true` if `IndexWriter.close()` should first commit before closing.

  - ### getIndexSort

    public Sort getIndexSort()
    Get the index-time `Sort` order, applied to all (flushed and merged) segments.

  - ### getIndexSortFields

    public Set<String> getIndexSortFields()
    Returns the field names involved in the index sort

  - ### getLeafSorter

    public Comparator<LeafReader> getLeafSorter()
    Returns a comparator for sorting leaf readers. If not `null`, this comparator is used to sort leaf readers within `DirectoryReader` opened from the `IndexWriter` of this configuration.
    Returns:
      a comparator for sorting leaf readers

  - ### isCheckPendingFlushOnUpdate

    public boolean isCheckPendingFlushOnUpdate()
    Expert: Returns if indexing threads check for pending flushes on update in order to help our flushing indexing buffers to disk
    WARNING: This API is experimental and might change in incompatible ways in the next release.

  - ### setCheckPendingFlushUpdate

    public LiveIndexWriterConfig setCheckPendingFlushUpdate(boolean checkPendingFlushOnUpdate)
    Expert: sets if indexing threads check for pending flushes on update in order to help our flushing indexing buffers to disk. As a consequence, threads calling `DirectoryReader.openIfChanged(DirectoryReader, IndexWriter)` or `IndexWriter.flush()` will be the only thread writing segments to disk unless flushes are falling behind. If indexing is stalled due to too many pending flushes indexing threads will help our writing pending segment flushes to disk.
    WARNING: This API is experimental and might change in incompatible ways in the next release.

  - ### getSoftDeletesField

    public String getSoftDeletesField()
    Returns the soft deletes field or `null` if soft-deletes are disabled. See `IndexWriterConfig.setSoftDeletesField(String)` for details.

  - ### getMaxFullFlushMergeWaitMillis

    public long getMaxFullFlushMergeWaitMillis()
    Expert: return the amount of time to wait for merges returned by by MergePolicy.findFullFlushMerges(...). If this time is reached, we proceed with the commit based on segments merged up to that point. The merges are not cancelled, and may still run to completion independent of the commit.

  - ### getIndexWriterEventListener

    public IndexWriterEventListener getIndexWriterEventListener()
    Returns the IndexWriterEventListener callback that tracks the key IndexWriter operations.

  - ### getParentField

    public String getParentField()
    Returns the parent document field name if configured.

  - ### toString

    public String toString()
    Overrides:
      `toString` in class `Object`