4 Jul
2012
4 Jul
'12
9:21 a.m.
Savitha,
Multilingual pages are expected to be made of document translations: each of the page
content is in one language which the author indicates and your indexer can read. This
should be your primary source of language detection and you should not need an automatic
language detector which is highly error-prone.
Your analyzers seem to be correct and I feel it is correct to index languages in different
fields.
I would recommend that you also use a default-text field (text_intl) which is only mildly
tokenized (whitespace, lowercase, ...) and that you add search into this field with much
lower boost.
As you say, you need "pre-processing of queries": I call this query expansion
but whatever the name I fully agree this is a necessary step, and one that is
insufficiently documented (on the solr side) and one that should be subclassable by
applications.
A part of it which is nicely documented is the Edismax qf parameters. It can contain, for
example:
title_en^3 title_fr^2 title_es^1.8 title_intl^1.7 text_en^1.5 text_fr^1.4 text_es^1.3
text_intl^1
you configure it into the solrconfig.xml which should also be adjustable I think.
I am still fearing that facetting by language is going to fail because you need to
consider an XWiki page in multiple language as multiple documents in the search results
which the user does not want (and which would break the principle of being a
translation).
Paul
Le 4 juil. 2012 à 07:05, savitha sundaramurthy a écrit :
Hi devs,
Here are my thoughts on the configuration for multi lingual support.
Solr uses different analysers and stemmers to index wiki content. This is
configured in a XML file, schema.xml.
The wiki content with english language is indexed with text_en field type
whereas french with text_fr field type. The language of the document is
fetched and appended to the field. ( fieldName +"_"+ language : title_en,
fulltext_en, space_en ).
Configurations below:
<!-- English -->
<fieldType name="text_en" class="solr.TextField"
positionIncrementGap="100">
<analyzer type="index">
<tokenizer class="solr.StandardTokenizerFactory"/>
<filter class="solr.StopFilterFactory" ignoreCase="true"
words="stopwords.txt" enablePositionIncrements="true" />
<filter class="solr.SynonymFilterFactory"
synonyms="index_synonyms.txt" ignoreCase="true"
expand="false"/>
<filter class="solr.LowerCaseFilterFactory"/>
<filter class="solr.EnglishMinimalStemFilterFactory"/>
</analyzer>
</fieldType>
<!-- French -->
<fieldType name="text_fr" class="solr.TextField"
positionIncrementGap="100">
<analyzer>
<tokenizer class="solr.StandardTokenizerFactory"/>
<!-- removes l', etc -->
<filter class="solr.ElisionFilterFactory" ignoreCase="true"
articles="lang/contractions_fr.txt"/>
<filter class="solr.LowerCaseFilterFactory"/>
<filter class="solr.StopFilterFactory" ignoreCase="true"
words="lang/stopwords_fr.txt" format="snowball"
enablePositionIncrements="true"/>
<filter class="solr.FrenchLightStemFilterFactory"/>
<!-- less aggressive: <filter
class="solr.FrenchMinimalStemFilterFactory"/> -->
<!-- more aggressive: <filter
class="solr.SnowballPorterFilterFactory"
language="French"/> -->
</analyzer>
</fieldType>
In the case of a document having multilingual text, say english and french.
There is no way to find the list of languages used in the document.
Is it good to use a language detection tool,
http://code.google.com/p/language-detection/ to get the list of languages,
if they are more than two use a multilingual field type ?
title_ml, space_ml, fulltext_ml, ml for multilingual.
<!-- Multilingual -->
<fieldType name="text_ml" class="solr.TextField"
positionIncrementGap="100">
<analyzer>
<tokenizer class="solr.StandardTokenizerFactory"/>
<!-- removes l', etc -->
<filter class="solr.LowerCaseFilterFactory"/>
<filter class="solr.StopFilterFactory" ignoreCase="true"
words="lang/stopwords_fr.txt" format="snowball"
enablePositionIncrements="true"/>
<filter class="solr.EnglishMinimalStemFilterFactory"/>
<filter class="solr.FrenchLightStemFilterFactory"/>
<filter class="solr.SpanishLightStemFilterFactory"/>
</analyzer>
</fieldType>
The list of analysers should match the languages supported by XWik instance.
Am planning to use language detection only to check whether text from
multiple languages exist. Will investigate if its possible to configure the
analysers on the fly based on the languages returned by the
language-detection tool.
Please suggest,if this is a right approach ?
--
Thanks,
Savitha.s
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