## Uses of Class
org.apache.lucene.index.MergePolicy

- Packages that use MergePolicy
  Package | Description
  --- | ---
  org.apache.lucene.index | Code to maintain and access indices.

- - ### Uses of MergePolicy in org.apache.lucene.index

    Subclasses of MergePolicy in org.apache.lucene.index
    Modifier and Type | Class and Description
    --- | ---
    `class` | `FilterMergePolicy` A wrapper for `MergePolicy` instances.
    `class` | `LogByteSizeMergePolicy` This is a `LogMergePolicy` that measures size of a segment as the total byte size of the segment's files.
    `class` | `LogDocMergePolicy` This is a `LogMergePolicy` that measures size of a segment as the number of documents (not taking deletions into account).
    `class` | `LogMergePolicy` This class implements a `MergePolicy` that tries to merge segments into levels of exponentially increasing size, where each level has fewer segments than the value of the merge factor.
    `class` | `NoMergePolicy` A `MergePolicy` which never returns merges to execute.
    `class` | `OneMergeWrappingMergePolicy` A wrapping merge policy that wraps the `MergePolicy.OneMerge` objects returned by the wrapped merge policy.
    `class` | `SoftDeletesRetentionMergePolicy` This `MergePolicy` allows to carry over soft deleted documents across merges.
    `class` | `TieredMergePolicy` Merges segments of approximately equal size, subject to an allowed number of segments per tier.
    `class` | `UpgradeIndexMergePolicy` This `MergePolicy` is used for upgrading all existing segments of an index when calling `IndexWriter.forceMerge(int)`.

    Fields in org.apache.lucene.index declared as MergePolicy
    Modifier and Type | Field and Description
    --- | ---
    `protected MergePolicy` | FilterMergePolicy.`in` The wrapped `MergePolicy`.
    `static MergePolicy` | NoMergePolicy.`INSTANCE` Singleton instance.
    `protected MergePolicy` | LiveIndexWriterConfig.`mergePolicy` `MergePolicy` for selecting merges.

    Methods in org.apache.lucene.index that return MergePolicy
    Modifier and Type | Method and Description
    --- | ---
    `MergePolicy` | IndexWriterConfig.`getMergePolicy()`
    `MergePolicy` | LiveIndexWriterConfig.`getMergePolicy()` Returns the current MergePolicy in use by this writer.

    Methods in org.apache.lucene.index with parameters of type MergePolicy
    Modifier and Type | Method and Description
    --- | ---
    `IndexWriterConfig` | IndexWriterConfig.`setMergePolicy(MergePolicy mergePolicy)`
    `LiveIndexWriterConfig` | LiveIndexWriterConfig.`setMergePolicy(MergePolicy mergePolicy)` Expert: `MergePolicy` is invoked whenever there are changes to the segments in the index.

    Constructors in org.apache.lucene.index with parameters of type MergePolicy
    Constructor and Description
    `FilterMergePolicy(MergePolicy in)` Creates a new filter merge policy instance wrapping another.
    `OneMergeWrappingMergePolicy(MergePolicy in, UnaryOperator<MergePolicy.OneMerge> wrapOneMerge)` Constructor
    `SoftDeletesRetentionMergePolicy(String field, Supplier<Query> retentionQuerySupplier, MergePolicy in)` Creates a new `SoftDeletesRetentionMergePolicy`
    `UpgradeIndexMergePolicy(MergePolicy in)` Wrap the given `MergePolicy` and intercept forceMerge requests to only upgrade segments written with previous Lucene versions.

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