Examples of TaxonomyWriter

org.apache.lucene.facet.taxonomy.TaxonomyWriter

TaxonomyWriter is the interface which the faceted-search library uses to dynamically build the taxonomy at indexing time.

Notes about concurrent access to the taxonomy:

An implementation must allow multiple readers and a single writer to be active concurrently. Readers follow so-called "point in time" semantics, i.e., a reader object will only see taxonomy entries which were available at the time it was created. What the writer writes is only available to (new) readers after the writer's commit() is called.

Faceted search keeps two indices - namely Lucene's main index, and this taxonomy index. When one or more readers are active concurrently with the writer, care must be taken to avoid an inconsistency between the state of these two indices: When writing to the indices, the taxonomy must always be committed to disk *before* the main index, because the main index refers to categories listed in the taxonomy. Such control can best be achieved by turning off the main index's "autocommit" feature, and explicitly calling commit() for both indices (first for the taxonomy, then for the main index). In old versions of Lucene (2.2 or earlier), when autocommit could not be turned off, a more complicated solution needs to be used. E.g., use some sort of (possibly inter-process) locking to ensure that a reader is being opened only right after both indices have been flushed (and before anything else is written to them). @lucene.experimental

    dir = newDirectory();
    RandomIndexWriter writer = new RandomIndexWriter(random, dir, 
        newIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(random, MockTokenizer.KEYWORD, false)));
    
    taxoDir = newDirectory();
    TaxonomyWriter taxoWriter = new LuceneTaxonomyWriter(taxoDir);
    
    for (int i = 0; i < 100; i++) {
      ArrayList<CategoryPath> paths = new ArrayList<CategoryPath>();
      Document doc = new Document();
      if (i % 2 == 0) { // 50
        doc.add(new Field("content", "foo", Store.NO, Index.ANALYZED));
      }
      if (i % 3 == 0) { // 33
        doc.add(new Field("content", "bar", Store.NO, Index.ANALYZED));
      }
      if (i % 4 == 0) { // 25
        paths.add(new CategoryPath("a"));
      }
      if (i % 5 == 0) { // 20
        paths.add(new CategoryPath("b"));
      }
      CategoryDocumentBuilder builder = new CategoryDocumentBuilder(taxoWriter);
      builder.setCategoryPaths(paths).build(doc);
      writer.addDocument(doc);
    }
    
    taxoWriter.close();
    reader = writer.getReader();
    writer.close();
    
    taxo = new LuceneTaxonomyReader(taxoDir);
  }

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Examples of TaxonomyWriter

Examples of org.apache.lucene.facet.taxonomy.TaxonomyWriter