# Package org.apache.lucene.facet.taxonomy.writercache.cl2o

Category->Ordinal caching implementation using an optimized data-structures

See: Description

- Class Summary
  Class | Description
  --- | ---
  Cl2oTaxonomyWriterCache | `TaxonomyWriterCache` using `CompactLabelToOrdinal`.
  CollisionMap | HashMap to store colliding labels.
  CompactLabelToOrdinal | This is a very efficient LabelToOrdinal implementation that uses a CharBlockArray to store all labels and a configurable number of HashArrays to reference the labels.
  LabelToOrdinal | Abstract class for storing Label->Ordinal mappings in a taxonomy.

## Package org.apache.lucene.facet.taxonomy.writercache.cl2o Description

# Category->Ordinal caching implementation using an optimized data-structures

The internal map data structure consumes less memory (~30%) and is faster (~50%) compared to a Java HashMap<String, Integer>.

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