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https://issues.apache.org/jira/browse/LUCENE-4499?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15320619#comment-15320619
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Michael McCandless commented on LUCENE-4499:
--------------------------------------------
LUCENE-6664 fixes the multi-term synonym problems "correctly", meaning the
synonym filter produces a correct graph, which e.g. a query parser could then
do the right thing with ... but the patch proved controversial so it won't be
committed any time soon.
But it's quite standalone in the patch (just another {{TokenFilter}}) so you
could maybe plug it into Solr and try it out.
> 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, 6.0
> Reporter: Roman Chyla
> Labels: analysis, multi-word, synonyms
> Fix For: 6.0
>
> Attachments: LUCENE-4499.patch, 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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