org.apache.lucene.index

## Class MultiPassIndexSplitter

- java.lang.Object
- - org.apache.lucene.index.MultiPassIndexSplitter

-     public class MultiPassIndexSplitter
      extends Object

  This tool splits input index into multiple equal parts. The method employed here uses `IndexWriter.addIndexes(CodecReader[])` where the input data comes from the input index with artificially applied deletes to the document id-s that fall outside the selected partition.

  Note 1: Deletes are only applied to a buffered list of deleted docs and don't affect the source index - this tool works also with read-only indexes.

  Note 2: the disadvantage of this tool is that source index needs to be read as many times as there are parts to be created, hence the name of this tool.

  NOTE: this tool is unaware of documents added atomically via `IndexWriter.addDocuments(java.lang.Iterable<? extends java.lang.Iterable<? extends org.apache.lucene.index.IndexableField>>)` or `IndexWriter.updateDocuments(org.apache.lucene.index.Term, java.lang.Iterable<? extends java.lang.Iterable<? extends org.apache.lucene.index.IndexableField>>)`, which means it can easily break up such document groups.

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `MultiPassIndexSplitter()`

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static void` | `main(String[] args)`
    `void` | `split(IndexReader in, Directory[] outputs, boolean seq)` Split source index into multiple parts.

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

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

- - ### Constructor Detail

    - #### MultiPassIndexSplitter

          public MultiPassIndexSplitter()

  - ### Method Detail

    - #### split

          public void split(IndexReader in,
                            Directory[] outputs,
                            boolean seq)
                     throws IOException

      Split source index into multiple parts.
      Parameters:
        `in` - source index, can have deletions, can have multiple segments (or multiple readers).
        `outputs` - list of directories where the output parts will be stored.
        `seq` - if true, then the source index will be split into equal increasing ranges of document id-s. If false, source document id-s will be assigned in a deterministic round-robin fashion to one of the output splits.
      Throws:
        `IOException` - If there is a low-level I/O error

    - #### main

          public static void main(String[] args)
                           throws Exception

      Throws:
        `Exception`

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