Lucene 4.7.2 misc API

Misc Tools


org.apache.lucene.document Misc extensions of the Document/Field API.
org.apache.lucene.index Misc index tools and index support.
org.apache.lucene.index.sorter Provides index sorting capablities.
org.apache.lucene.misc Miscellaneous index tools. Misc Directory implementations.
org.apache.lucene.util.fst Misc FST classes.


Misc Tools

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


NOTE: This uses C++ sources (accessible via JNI), which you'll have to compile on your platform.

NativeUnixDirectory 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. Steps to build:

NativePosixUtil.cpp/java also expose access to the posix_madvise, madvise, posix_fadvise functions, which are somewhat more cross platform than O_DIRECT, however, in testing (see above link), these APIs did not seem to help prevent buffer cache eviction.

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