1<!-- 2 Licensed to the Apache Software Foundation (ASF) under one or more 3 contributor license agreements. See the NOTICE file distributed with 4 this work for additional information regarding copyright ownership. 5 The ASF licenses this file to You under the Apache License, Version 2.0 6 (the "License"); you may not use this file except in compliance with 7 the License. You may obtain a copy of the License at 8 9 http://www.apache.org/licenses/LICENSE-2.0 10 11 Unless required by applicable law or agreed to in writing, software 12 distributed under the License is distributed on an "AS IS" BASIS, 13 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 See the License for the specific language governing permissions and 15 limitations under the License. 16--> 17<html> 18 <head> 19 <title> 20 miscellaneous 21 </title> 22 </head> 23 <body> 24 25<h1>Misc Tools</h1> 26 27The misc package has various tools for splitting/merging indices, 28changing norms, finding high freq terms, and others. 29 30<a id="DirectIODirectory"></a> 31<h2>DirectIODirectory</h2> 32 33<p> 34{@link org.apache.lucene.misc.store.DirectIODirectory} is a Directory implementation that bypasses the 35OS's buffer cache (using direct IO) for any IndexInput and IndexOutput 36used during merging of segments larger than a specified size (default 3710 MB). This avoids evicting hot pages that are still in-use for 38searching, keeping search more responsive while large merges run. 39 40<p> 41See <a target="_top" href="http://blog.mikemccandless.com/2010/06/lucene-and-fadvisemadvise.html">this blog post</a> 42for details. 43 44</body> 45 46</html> 47