org.apache.lucene.index

## Interface MergePolicy.MergeContext

- All Known Implementing Classes:
    IndexWriter
  Enclosing class:
    MergePolicy

      public static interface MergePolicy.MergeContext

  This interface represents the current context of the merge selection process. It allows to access real-time information like the currently merging segments or how many deletes a segment would claim back if merged. This context might be stateful and change during the execution of a merge policy's selection processes.
  WARNING: This API is experimental and might change in incompatible ways in the next release.

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method and Description
    --- | ---
    `InfoStream` | `getInfoStream()` Returns the info stream that can be used to log messages
    `Set<SegmentCommitInfo>` | `getMergingSegments()` Returns an unmodifiable set of segments that are currently merging.
    `int` | `numDeletedDocs(SegmentCommitInfo info)` Returns the number of deleted documents in the given segments.
    `int` | `numDeletesToMerge(SegmentCommitInfo info)` Returns the number of deletes a merge would claim back if the given segment is merged.

- - ### Method Detail

    - #### numDeletesToMerge

          int numDeletesToMerge(SegmentCommitInfo info)
                         throws IOException

      Returns the number of deletes a merge would claim back if the given segment is merged.
      Parameters:
        `info` - the segment to get the number of deletes for
      Throws:
        `IOException`
      See Also:
        `MergePolicy.numDeletesToMerge(SegmentCommitInfo, int, org.apache.lucene.util.IOSupplier)`

    - #### numDeletedDocs

          int numDeletedDocs(SegmentCommitInfo info)

      Returns the number of deleted documents in the given segments.

    - #### getInfoStream

          InfoStream getInfoStream()

      Returns the info stream that can be used to log messages

    - #### getMergingSegments

          Set<SegmentCommitInfo> getMergingSegments()

      Returns an unmodifiable set of segments that are currently merging.

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