# Package org.apache.lucene.facet.taxonomy.directory

Taxonomy index implementation using on top of a Directory.

See: Description

Interface Summary
Interface | Description
--- | ---
DirectoryTaxonomyWriter.OrdinalMap | Mapping from old ordinal to new ordinals, used when merging indexes wit separate taxonomies.

Class Summary
Class | Description
--- | ---
DirectoryTaxonomyReader | A `TaxonomyReader` which retrieves stored taxonomy information from a `Directory`.
DirectoryTaxonomyWriter | `TaxonomyWriter` which uses a `Directory` to store the taxonomy information on disk, and keeps an additional in-memory cache of some or all categories.
DirectoryTaxonomyWriter.DiskOrdinalMap | `DirectoryTaxonomyWriter.OrdinalMap` maintained on file system
DirectoryTaxonomyWriter.MemoryOrdinalMap | `DirectoryTaxonomyWriter.OrdinalMap` maintained in memory
ParallelTaxonomyArrays | Returns 3 arrays for traversing the taxonomy: `parents`: `parents[i]` denotes the parent of category ordinal `i`. `children`: `children[i]` denotes the youngest child of category ordinal `i`.

## Package org.apache.lucene.facet.taxonomy.directory Description

Taxonomy index implementation using on top of a Directory.