Details
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Improvement
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Status: Closed
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Minor
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Resolution: Fixed
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3.6, 4.0-ALPHA
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None
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All
Description
SOLR-2438 creates a new MultiTermAwareComponent interface. This allows Solr to automatically assemble a "multiterm" analyzer that does the right thing vis-a-vis transforming the individual terms of a multi-term query at query time. Examples are: lower casing, folding accents, etc. Currently (27-Nov-2011), the following classes implement MultiTermAwareComponent:
- ASCIIFoldingFilterFactory
- LowerCaseFilterFactory
- LowerCaseTokenizerFactory
- MappingCharFilterFactory
- PersianCharFilterFactory
When users put any of the above in their query analyzer, Solr will "do the right thing" at query time and the perennial question users have, "why didn't my wildcard query automatically lower-case (or accent fold or....) my terms?" will be gone. Die question die!
But taking a quick look, for instance, at the various FilterFactories that exist, there are a number of possibilities that might be good candidates for implementing MultiTermAwareComponent. But I really don't understand the correct behavior here well enough to know whether these should implement the interface or not. And this doesn't include other CharFilters or Tokenizers.
Actually implementing the interface is often trivial, see the classes above for examples. Note that LowerCaseTokenizerFactory returns a Filter, which is the right thing in this case.
Here is a quick cull of the Filters that, just from their names, might be candidates. If anyone wants to take any of them on, that would be great. If all you can do is provide test cases, I could probably do the code part, just let me know.
ArabicNormalizationFilterFactory
GreekLowerCaseFilterFactory
HindiNormalizationFilterFactory
ICUFoldingFilterFactory
ICUNormalizer2FilterFactory
ICUTransformFilterFactory
IndicNormalizationFilterFactory
ISOLatin1AccentFilterFactory
PersianNormalizationFilterFactory
RussianLowerCaseFilterFactory
TurkishLowerCaseFilterFactory