# 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>.