Misc Tools

The misc package has various tools for splitting/merging indices, changing norms, finding high freq terms, and others.

DirectIODirectory

DirectIODirectory is a Directory implementation that bypasses the OS's buffer cache (using direct IO) for any IndexInput and IndexOutput used during merging of segments larger than a specified size (default 10 MB). This avoids evicting hot pages that are still in-use for searching, keeping search more responsive while large merges run.

See this blog post for details.

Packages

Package	Description
org.apache.lucene.misc	Miscellaneous Lucene utilities that don't really fit anywhere else.
org.apache.lucene.misc.document	Misc extensions of the Document/Field API.
org.apache.lucene.misc.index	Misc index tools and index support.
org.apache.lucene.misc.search	Misc search implementations.
org.apache.lucene.misc.store	Misc Directory implementations.
org.apache.lucene.misc.util	Memory Tracker interface which allows defining custom collector level memory trackers
org.apache.lucene.misc.util.fst	Misc FST classes.