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From "Nolan Lawson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-4499) Multi-word synonym filter (synonym expansion)
Date Sun, 02 Dec 2012 17:45:59 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-4499?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13508304#comment-13508304
] 

Nolan Lawson commented on LUCENE-4499:
--------------------------------------

@Robert: Thanks for the clarification.  I've corrected my blog post.

@Roman: Yes, I think it's a very common use case.  Especially considering that your query
expander seems to be doing the same thing as ours!

My idea with the custom QueryParserPlugin was just to have a self-contained solution that
didn't mess with the core Lucene/Solr logic too much.  And I think it's still configurable
enough that it can handle your case-insensitivity tweaks (which I totally understand - "MIT"
is not the same thing as "mit").  You'd just have to have some pretty fancy XML in the "synonymAnalyzers"
section. :)
                
> Multi-word synonym filter (synonym expansion)
> ---------------------------------------------
>
>                 Key: LUCENE-4499
>                 URL: https://issues.apache.org/jira/browse/LUCENE-4499
>             Project: Lucene - Core
>          Issue Type: Improvement
>          Components: core/other
>    Affects Versions: 4.1, 5.0
>            Reporter: Roman Chyla
>            Priority: Minor
>              Labels: analysis, multi-word, synonyms
>             Fix For: 5.0
>
>         Attachments: LUCENE-4499.patch
>
>
> I apologize for bringing the multi-token synonym expansion up again. There is an old,
unresolved issue at LUCENE-1622 [1]
> While solving the problem for our needs [2], I discovered that the current SolrSynonym
parser (and the wonderful FTS) have almost everything to satisfactorily handle both the query
and index time synonym expansion. It seems that people often need to use the synonym filter
*slightly* differently at indexing and query time.
> In our case, we must do different things during indexing and querying.
> Example sentence: Mirrors of the Hubble space telescope pointed at XA5
> This is what we need (comma marks position bump):
> indexing: mirrors,hubble|hubble space telescope|hst,space,telescope,pointed,xa5|astroobject#5
> querying: +mirrors +(hubble space telescope | hst) +pointed +(xa5|astroboject#5)
> This translated to following needs:
>   indexing time: 
>     single-token synonyms => return only synonyms
>     multi-token synonyms => return original tokens *AND* the synonyms
>   query time:
>     single-token: return only synonyms (but preserve case)
>     multi-token: return only synonyms
>  
> We need the original tokens for the proximity queries, if we indexed 'hubble space telescope'
> as one token, we cannot search for 'hubble NEAR telescope'
> You may (not) be surprised, but Lucene already supports ALL of these requirements. The
patch is an attempt to state the problem differently. I am not sure if it is the best option,
however it works perfectly for our needs and it seems it could work for general public too.
Especially if the SynonymFilterFactory had a preconfigured sets of SynonymMapBuilders - and
people would just choose what situation they use. Please look at the unittest.
> links:
> [1] https://issues.apache.org/jira/browse/LUCENE-1622
> [2] http://labs.adsabs.harvard.edu/trac/ads-invenio/ticket/158
> [3] seems to have similar request: http://lucene.472066.n3.nabble.com/Proposal-Full-support-for-multi-word-synonyms-at-query-time-td4000522.html

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