Package org.apache.lucene.facet.taxonomy

Class OrdinalMappingLeafReader

  • All Implemented Interfaces:
    Closeable, AutoCloseable
    public class OrdinalMappingLeafReader
extends FilterLeafReader
    A FilterLeafReader for updating facets ordinal references, based on an ordinal map. You should use this code in conjunction with merging taxonomies - after you merge taxonomies, you receive an DirectoryTaxonomyWriter.OrdinalMap which maps the 'old' ordinals to the 'new' ones. You can use that map to re-map the doc values which contain the facets information (ordinals) either before or while merging the indexes.

    For re-mapping the ordinals during index merge, do the following: 

     // merge the old taxonomy with the new one.
 OrdinalMap map = new MemoryOrdinalMap();
 DirectoryTaxonomyWriter.addTaxonomy(srcTaxoDir, map);
 int[] ordmap = map.getMap();

 // Add the index and re-map ordinals on the go
 DirectoryReader reader = DirectoryReader.open(oldDir);
 IndexWriterConfig conf = new IndexWriterConfig(VER, ANALYZER);
 IndexWriter writer = new IndexWriter(newDir, conf);
 List<LeafReaderContext> leaves = reader.leaves();
 LeafReader wrappedLeaves[] = new LeafReader[leaves.size()];
 for (int i = 0; i < leaves.size(); i++) {
   wrappedLeaves[i] = new OrdinalMappingLeafReader(leaves.get(i).reader(), ordmap);
 }
 writer.addIndexes(new MultiReader(wrappedLeaves));
 writer.commit();
    WARNING: This API is experimental and might change in incompatible ways in the next release.