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| <html> |
| <head> |
| <title> |
| miscellaneous |
| </title> |
| </head> |
| <body> |
| |
| <h2>Misc Tools</h2> |
| |
| The misc package has various tools for splitting/merging indices, |
| changing norms, finding high freq terms, and others. |
| |
| <a name="NativeUnixDirectory"></a> |
| <h2>NativeUnixDirectory</h2> |
| |
| <p> |
| <b>NOTE</b>: This uses C++ sources (accessible via JNI), which you'll |
| have to compile on your platform. |
| |
| <p> |
| {@link org.apache.lucene.store.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. |
| |
| <p> |
| See <a target=_top href="http://blog.mikemccandless.com/2010/06/lucene-and-fadvisemadvise.html">this blog post</a> |
| for details. |
| |
| Steps to build: |
| <ul> |
| <li> <tt>cd lucene/misc/</tt> |
| |
| <li> To compile NativePosixUtil.cpp -> libNativePosixUtil.so, run<tt> ant build-native-unix</tt>. |
| |
| <li><tt>libNativePosixUtil.so</tt> will be located in the <tt>lucene/build/native/</tt> folder |
| |
| <li> Make sure libNativePosixUtil.so is on your LD_LIBRARY_PATH so java can find it (something like <tt>export LD_LIBRARY_PATH=/path/to/dir:$LD_LIBRARY_PATH</tt>, where /path/to/dir contains libNativePosixUtil.so) |
| |
| <li> <tt>ant jar</tt> to compile the java source and put that JAR on your CLASSPATH |
| </ul> |
| |
| <p> |
| 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. |
| </body> |
| |
| </html> |
