Package org.opensearch.index.analysis

Class ICUCollationKeyFilter

java.lang.Object
org.apache.lucene.util.AttributeSource
org.apache.lucene.analysis.TokenStream
org.apache.lucene.analysis.TokenFilter
org.opensearch.index.analysis.ICUCollationKeyFilter
All Implemented Interfaces:
Closeable, AutoCloseable, Unwrappable<org.apache.lucene.analysis.TokenStream>
@Deprecated public final class ICUCollationKeyFilter extends org.apache.lucene.analysis.TokenFilter
Deprecated.
Use ICUCollationDocValuesField instead, which encodes terms directly as bytes. This filter WAS removed in Lucene 5.0

Converts each token into its CollationKey, and then encodes the CollationKey with IndexableBinaryStringTools, to allow it to be stored as an index term.

WARNING: Make sure you use exactly the same Collator at index and query time -- CollationKeys are only comparable when produced by the same Collator. RuleBasedCollators are independently versioned, so it is safe to search against stored CollationKeys if the following are exactly the same (best practice is to store this information with the index and check that they remain the same at query time):

  1. Collator version - see Collator.getVersion()
  2. The collation strength used - see Collator.setStrength(int)

CollationKeys generated by ICU Collators are not compatible with those generated by java.text.Collators. Specifically, if you use ICUCollationKeyFilter to generate index terms, do not use CollationKeyFilter on the query side, or vice versa.

ICUCollationKeyFilter is significantly faster and generates significantly shorter keys than CollationKeyFilter. See http://site.icu-project.org/charts/collation-icu4j-sun for key generation timing and key length comparisons between ICU4J and java.text.Collator over several languages.

  • Constructor Details

    • ICUCollationKeyFilter

      public ICUCollationKeyFilter(org.apache.lucene.analysis.TokenStream input, com.ibm.icu.text.Collator collator)
      Deprecated.
      Parameters:
      input - Source token stream
      collator - CollationKey generator

  • Method Details

    • incrementToken

      public boolean incrementToken() throws IOException
      Deprecated.
      Specified by:
      incrementToken in class org.apache.lucene.analysis.TokenStream
      Throws:
      IOException