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Posted to dev@lucene.apache.org by "Uwe Schindler (JIRA)" <ji...@apache.org> on 2013/05/10 01:05:38 UTC
[jira] [Updated] (LUCENE-3843) implement PositionLengthAttribute
for all tokenstreams where its appropriate
[ https://issues.apache.org/jira/browse/LUCENE-3843?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Uwe Schindler updated LUCENE-3843:
----------------------------------
Fix Version/s: (was: 4.3)
4.4
> implement PositionLengthAttribute for all tokenstreams where its appropriate
> ----------------------------------------------------------------------------
>
> Key: LUCENE-3843
> URL: https://issues.apache.org/jira/browse/LUCENE-3843
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: Robert Muir
> Fix For: 4.4
>
>
> LUCENE-3767 introduces PositionLengthAttribute, which extends the tokenstream API
> from a sausage to a real graph.
> Currently tokenstreams such as WordDelimiterFilter and SynonymsFilter theoretically
> work at a graph level, but then serialize themselves to a sausage, for example:
> wi-fi with WDF creates:
> wi(posinc=1), fi(posinc=1), wifi(posinc=0)
> So the lossiness is that the 'wifi' is simply stacked ontop of 'fi'
> PositionLengthAttribute fixes this by allowing a token to declare how far it "spans",
> so we don't lose any information.
> While the indexer currently can only support sausages anyway (and for performance reasons,
> this is probably just fine!), other tokenstream consumers such as queryparsers and suggesters
> such as LUCENE-3842 can actually make use of this information for better behavior.
> So I think its ideal if the TokenStream API doesn't reflect the lossiness of the index format,
> but instead keeps all information, and after LUCENE-3767 is committed we should fix tokenstreams
> to preserve this information for consumers that can use it.
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