Class IndexWriterConfig

  • All Implemented Interfaces:
    Cloneable

    public final class IndexWriterConfig
    extends Object
    implements Cloneable
    Holds all the configuration of IndexWriter. You should instantiate this class, call the setters to set your configuration, then pass it to IndexWriter. Note that IndexWriter makes a private clone; if you need to subsequently change settings use IndexWriter.getConfig().

    All setter methods return IndexWriterConfig to allow chaining settings conveniently, for example:

     IndexWriterConfig conf = new IndexWriterConfig(analyzer);
     conf.setter1().setter2();
     
    Since:
    3.1
    • Field Detail

      • DISABLE_AUTO_FLUSH

        public static final int DISABLE_AUTO_FLUSH
        Denotes a flush trigger is disabled.
        See Also:
        Constant Field Values
      • DEFAULT_MAX_BUFFERED_DELETE_TERMS

        public static final int DEFAULT_MAX_BUFFERED_DELETE_TERMS
        Disabled by default (because IndexWriter flushes by RAM usage by default).
        See Also:
        Constant Field Values
      • DEFAULT_MAX_BUFFERED_DOCS

        public static final int DEFAULT_MAX_BUFFERED_DOCS
        Disabled by default (because IndexWriter flushes by RAM usage by default).
        See Also:
        Constant Field Values
      • DEFAULT_RAM_BUFFER_SIZE_MB

        public static final double DEFAULT_RAM_BUFFER_SIZE_MB
        Default value is 16 MB (which means flush when buffered docs consume approximately 16 MB RAM).
        See Also:
        Constant Field Values
      • DEFAULT_MAX_THREAD_STATES

        public static final int DEFAULT_MAX_THREAD_STATES
        The maximum number of simultaneous threads that may be indexing documents at once in IndexWriter; if more than this many threads arrive they will wait for others to finish.
        See Also:
        Constant Field Values
      • DEFAULT_READER_TERMS_INDEX_DIVISOR

        public static final int DEFAULT_READER_TERMS_INDEX_DIVISOR
        Default value is 1. Change using setReaderTermsIndexDivisor(int).
    • Method Detail

      • setDefaultWriteLockTimeout

        public static void setDefaultWriteLockTimeout​(long writeLockTimeout)
        Sets the default (for any instance) maximum time to wait for a write lock (in milliseconds).
      • getDefaultWriteLockTimeout

        public static long getDefaultWriteLockTimeout()
        Returns the default write lock timeout for newly instantiated IndexWriterConfigs.
        See Also:
        setDefaultWriteLockTimeout(long)
      • getAnalyzer

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

        public IndexWriterConfig setIndexDeletionPolicy​(IndexDeletionPolicy delPolicy)
        Expert: allows an optional IndexDeletionPolicy implementation to be specified. You can use this to control when prior commits are deleted from the index. The default policy is KeepOnlyLastCommitDeletionPolicy which removes all prior commits as soon as a new commit is done (this matches behavior before 2.2). Creating your own policy can allow you to explicitly keep previous "point in time" commits alive in the index for some time, to allow readers to refresh to the new commit without having the old commit deleted out from under them. This is necessary on filesystems like NFS that do not support "delete on last close" semantics, which Lucene's "point in time" search normally relies on.

        NOTE: the deletion policy cannot be null. If null is passed, the deletion policy will be set to the default.

        Only takes effect when IndexWriter is first created.

      • setIndexCommit

        public IndexWriterConfig setIndexCommit​(IndexCommit commit)
        Expert: allows to open a certain commit point. The default is null which opens the latest commit point.

        Only takes effect when IndexWriter is first created.

      • setTermIndexInterval

        public IndexWriterConfig setTermIndexInterval​(int interval)
        Expert: set the interval between indexed terms. Large values cause less memory to be used by IndexReader, but slow random-access to terms. Small values cause more memory to be used by an IndexReader, and speed random-access to terms.

        This parameter determines the amount of computation required per query term, regardless of the number of documents that contain that term. In particular, it is the maximum number of other terms that must be scanned before a term is located and its frequency and position information may be processed. In a large index with user-entered query terms, query processing time is likely to be dominated not by term lookup but rather by the processing of frequency and positional data. In a small index or when many uncommon query terms are generated (e.g., by wildcard queries) term lookup may become a dominant cost.

        In particular, numUniqueTerms/interval terms are read into memory by an IndexReader, and, on average, interval/2 terms must be scanned for each random term access.

        See Also:
        Takes effect immediately, but only applies to newly flushed/merged segments.
      • getTermIndexInterval

        public int getTermIndexInterval()
        Returns the interval between indexed terms.
        See Also:
        setTermIndexInterval(int)
      • setMergeScheduler

        public IndexWriterConfig setMergeScheduler​(MergeScheduler mergeScheduler)
        Expert: sets the merge scheduler used by this writer. The default is ConcurrentMergeScheduler.

        NOTE: the merge scheduler cannot be null. If null is passed, the merge scheduler will be set to the default.

        Only takes effect when IndexWriter is first created.

      • setWriteLockTimeout

        public IndexWriterConfig setWriteLockTimeout​(long writeLockTimeout)
        Sets the maximum time to wait for a write lock (in milliseconds) for this instance. You can change the default value for all instances by calling setDefaultWriteLockTimeout(long).

        Only takes effect when IndexWriter is first created.

      • getWriteLockTimeout

        public long getWriteLockTimeout()
        Returns allowed timeout when acquiring the write lock.
        See Also:
        setWriteLockTimeout(long)
      • getMaxBufferedDeleteTerms

        public int getMaxBufferedDeleteTerms()
        Returns the number of buffered deleted terms that will trigger a flush if enabled.
        See Also:
        setMaxBufferedDeleteTerms(int)
      • setRAMBufferSizeMB

        public IndexWriterConfig 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 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.

        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() periodically yourself, or by using setMaxBufferedDeleteTerms(int) to flush by count instead of RAM usage (each buffered delete Query counts as one).

        NOTE: because IndexWriter uses ints when managing its internal storage, the absolute maximum value for this setting is somewhat less than 2048 MB. The precise limit depends on various factors, such as how large your documents are, how many fields have norms, etc., so it's best to set this value comfortably under 2048.

        The default value is 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
      • setMaxBufferedDocs

        public IndexWriterConfig 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 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)
      • setMaxThreadStates

        public IndexWriterConfig setMaxThreadStates​(int maxThreadStates)
        Sets the max number of simultaneous threads that may be indexing documents at once in IndexWriter. Values < 1 are invalid and if passed maxThreadStates will be set to DEFAULT_MAX_THREAD_STATES.

        Only takes effect when IndexWriter is first created.

      • getMaxThreadStates

        public int getMaxThreadStates()
        Returns the max number of simultaneous threads that may be indexing documents at once in IndexWriter.
      • setReaderPooling

        public IndexWriterConfig setReaderPooling​(boolean readerPooling)
        By default, IndexWriter does not pool the SegmentReaders it must open for deletions and merging, unless a near-real-time reader has been obtained by calling IndexWriter.getReader(). This method lets you enable pooling without getting a near-real-time reader. NOTE: if you set this to false, IndexWriter will still pool readers once IndexWriter.getReader() is called.

        Only takes effect when IndexWriter is first created.

      • getReaderPooling

        public boolean getReaderPooling()
        Returns true if IndexWriter should pool readers even if IndexWriter.getReader() has not been called.
      • setReaderTermsIndexDivisor

        public IndexWriterConfig setReaderTermsIndexDivisor​(int divisor)
        Sets the termsIndexDivisor passed to any readers that IndexWriter opens, for example when applying deletes or creating a near-real-time reader in IndexWriter.getReader(). If you pass -1, the terms index won't be loaded by the readers. This is only useful in advanced situations when you will only .next() through all terms; attempts to seek will hit an exception.

        Takes effect immediately, but only applies to readers opened after this call