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-<head>
- <title>InstantiatedIndex</title>
-</head>
-<body>
-<p>InstantiatedIndex, alternative RAM store for small corpora.</p>
-
-<p>@lucene.experimental</p>
-<h2>Abstract</h2>
-
-<p>
- Represented as a coupled graph of class instances, this
- all-in-memory index store implementation delivers search
- results up to a 100 times faster than the file-centric RAMDirectory
- at the cost of greater RAM consumption.
-</p>
-
-<h2>API</h2>
-
-<p>
- Just as the default store implementation, InstantiatedIndex
- comes with an IndexReader and IndexWriter. The latter share
- many method signatures with the file-centric IndexWriter.
-</p>
-
-<p>
- It is also possible to load the content of another index
- by passing an IndexReader to the InstantiatedIndex constructor.
-</p>
-
-<h2>Performance</h2>
-
-<p>
- At a few thousand ~160 characters long documents
- InstantiatedIndex outperforms RAMDirectory some 50x,
- 15x at 100 documents of 2000 characters length,
- and is linear to RAMDirectory at 10,000 documents of 2000 characters length.
-</p>
-
-<p>Mileage may vary depending on term saturation.</p>
-
-<img src="doc-files/HitCollectionBench.jpg" alt="benchmark"/>
-
-<p>
- Populated with a single document InstantiatedIndex is almost, but not quite, as fast as MemoryIndex.
-</p>
-
-<p>
- It takes more or less the same time to populate an InstantiatedIndex
- as it takes to populate a RAMDirectory. Hardly any effort has been put
- in to optimizing the InstantiatedIndexWriter, only minimizing the amount
- of time needed to write-lock the index has been considered.
-</p>
-
-<h2>Caveats</h2>
-<ul>
- <li>No locks! Consider using InstantiatedIndex as if it was immutable.</li>
- <li>No documents with fields containing readers.</li>
- <li>No field selection when retrieving documents, as all stored field are available in memory.</li>
- <li>Any document returned must cloned if they are to be touched.</li>
- <li>Norms array returned must not be touched.</li>
-</ul>
-
-<h2>Use cases</h2>
-
-<p>
- Could replace any small index that could do with greater response time.
- spell check a priori index,
- the index of new documents exposed to user search agent queries,
- to compile classifiers in machine learning environments, etc.
-</p>
-
-<h2>Class diagram</h2>
-<a href="doc-files/classdiagram.png"><img width="640px" height="480px" src="doc-files/classdiagram.png" alt="class diagram"></a>
-<br/>
-<a href="doc-files/classdiagram.uxf">Diagram</a> rendered using <a href="http://umlet.com">UMLet</a> 7.1.
-</body>
-</html>
fnp / pylucene.git / blobdiff