Add language analyzers to string fields in an Azure Cognitive Search index

  • 3 minutes to read

A language analyzer is a specific type of text analyzer that performs lexical analysis using the linguistic rules of the target language. Every searchable field has an analyzer property. If your index contains translated strings, such as separate fields for English and Chinese text, you could specify language analyzers on each field to access the rich linguistic capabilities of those analyzers.

Azure Cognitive Search supports 35 analyzers backed by Lucene, and 50 analyzers backed by proprietary Microsoft natural language processing technology used in Office and Bing.

Comparing analyzers

Some developers might prefer the more familiar, simple, open-source solution of Lucene. Lucene language analyzers are faster, but the Microsoft analyzers have advanced capabilities, such as lemmatization, word decompounding (in languages like German, Danish, Dutch, Swedish, Norwegian, Estonian, Finish, Hungarian, Slovak) and entity recognition (URLs, emails, dates, numbers). If possible, you should run comparisons of both the Microsoft and Lucene analyzers to decide which one is a better fit.

Indexing with Microsoft analyzers is on average two to three times slower than their Lucene equivalents, depending on the language. Search performance should not be significantly affected for average size queries.

English analyzers

The default analyzer is Standard Lucene, which works well for English, but perhaps not as well as Lucene's English analyzer or Microsoft's English analyzer.

  • Lucene's English analyzer extends the standard analyzer. It removes possessives (trailing 's) from words, applies stemming as per Porter Stemming algorithm, and removes English stop words.

  • Microsoft's English analyzer performs lemmatization instead of stemming. This means it can handle inflected and irregular word forms much better what results in more relevant search results

Configuring analyzers

Language analyzers are used as-is. For each field in the index definition, you can set the analyzer property to an analyzer name that specifies the language and linguistics stack (Microsoft or Lucene). The same analyzer will be applied when indexing and searching for that field. For example, you can have separate fields for English, French, and Spanish hotel descriptions that exist side by side in the same index.

Note

It is not possible to use a different language analyzer at indexing time than at query time for a field. That capability is reserved for custom analyzers. For this reason, if you try to set the searchAnalyzer or indexAnalyzer properties to the name of a language analyzer, the REST API will return an error response. You must use the analyzer property instead.

Use the searchFields query parameter to specify which language-specific field to search against in your queries. You can review query examples that include the analyzer property in Search Documents.

For more information about index properties, see Create Index (Azure Cognitive Search REST API). For more information about analysis in Azure Cognitive Search, see Analyzers in Azure Cognitive Search.

Language analyzer list

Below is the list of supported languages together with Lucene and Microsoft analyzer names.

Language Microsoft Analyzer Name Lucene Analyzer Name
Arabic ar.microsoft ar.lucene
Armenian hy.lucene
Bangla bn.microsoft
Basque eu.lucene
Bulgarian bg.microsoft bg.lucene
Catalan ca.microsoft ca.lucene
Chinese Simplified zh-Hans.microsoft zh-Hans.lucene
Chinese Traditional zh-Hant.microsoft zh-Hant.lucene
Croatian hr.microsoft
Czech cs.microsoft cs.lucene
Danish da.microsoft da.lucene
Dutch nl.microsoft nl.lucene
English en.microsoft en.lucene
Estonian et.microsoft
Finnish fi.microsoft fi.lucene
French fr.microsoft fr.lucene
Galician gl.lucene
German de.microsoft de.lucene
Greek el.microsoft el.lucene
Gujarati gu.microsoft
Hebrew he.microsoft
Hindi hi.microsoft hi.lucene
Hungarian hu.microsoft hu.lucene
Icelandic is.microsoft
Indonesian (Bahasa) id.microsoft id.lucene
Irish ga.lucene
Italian it.microsoft it.lucene
Japanese ja.microsoft ja.lucene
Kannada kn.microsoft
Korean ko.microsoft ko.lucene
Latvian lv.microsoft lv.lucene
Lithuanian lt.microsoft
Malayalam ml.microsoft
Malay (Latin) ms.microsoft
Marathi mr.microsoft
Norwegian nb.microsoft no.lucene
Persian fa.lucene
Polish pl.microsoft pl.lucene
Portuguese (Brazil) pt-Br.microsoft pt-Br.lucene
Portuguese (Portugal) pt-Pt.microsoft pt-Pt.lucene
Punjabi pa.microsoft
Romanian ro.microsoft ro.lucene
Russian ru.microsoft ru.lucene
Serbian (Cyrillic) sr-cyrillic.microsoft
Serbian (Latin) sr-latin.microsoft
Slovak sk.microsoft
Slovenian sl.microsoft
Spanish es.microsoft es.lucene
Swedish sv.microsoft sv.lucene
Tamil ta.microsoft
Telugu te.microsoft
Thai th.microsoft th.lucene
Turkish tr.microsoft tr.lucene
Ukrainian uk.microsoft
Urdu ur.microsoft
Vietnamese vi.microsoft

All analyzers with names annotated with Lucene are powered by Apache Lucene's language analyzers.

See also