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

Package 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

  Modifier and Type
  Method
  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 Details

  - ### 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`