org.apache.lucene.index

## Interface IndexWriter.IndexReaderWarmer

- All Known Implementing Classes:
    SimpleMergedSegmentWarmer
  Enclosing class:
    IndexWriter
  Functional Interface:
    This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

      @FunctionalInterface
      public static interface IndexWriter.IndexReaderWarmer

  If `DirectoryReader.open(IndexWriter)` has been called (ie, this writer is in near real-time mode), then after a merge completes, this class can be invoked to warm the reader on the newly merged segment, before the merge commits. This is not required for near real-time search, but will reduce search latency on opening a new near real-time reader after a merge completes.
  WARNING: This API is experimental and might change in incompatible ways in the next release.

    NOTE: `warm(LeafReader)` is called before any deletes have been carried over to the merged segment.

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `warm(LeafReader reader)` Invoked on the `LeafReader` for the newly merged segment, before that segment is made visible to near-real-time readers.

- - ### Method Detail

    - #### warm

          void warm(LeafReader reader)
             throws IOException

      Invoked on the `LeafReader` for the newly merged segment, before that segment is made visible to near-real-time readers.
      Throws:
        `IOException`

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