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https://issues.apache.org/jira/browse/JENA-1313?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15951031#comment-15951031
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Bruno P. Kinoshita commented on JENA-1313:
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Osma,
>I re-read the description of the Dydra implementation of collation, but they
>don't say what the ordering is between literals with differing language tags -
>it remains explicitly undefined, as in SPARQL. I don't know what ORDER BY will
>in practice do in Dydra when the language tags differ.
>From the blog post you shared, in the list where they explain the consequent
>logic:
>if the two terms do not agree in language tag, either because just one lacks a
>tag or because the tags are not identical, then the two terms are not ordered.
So my understanding is that the terms won't be ordered (maybe the comparator
returns 0 when that happens...).
>(...) and the language/locale (which may be omitted, and then the language is
>extracted from the language tag)
+1, this way we would also have a similar behaviour to Dydra's.
>In order to determine the effective collation sequence we extract the initial
>ISO 639-1 code from the language tag and use it to designate a locale, which
>in turn determines the collation.
Cheers
Bruno
> Language-specific collation in ARQ
> ----------------------------------
>
> Key: JENA-1313
> URL: https://issues.apache.org/jira/browse/JENA-1313
> Project: Apache Jena
> Issue Type: Improvement
> Components: ARQ
> Affects Versions: Jena 3.2.0
> Reporter: Osma Suominen
>
> As [discussed|http://markmail.org/message/v2bvsnsza5ksl2cv] on the users
> mailing list in October 2016, I would like to change ARQ collation of literal
> values to be language-aware and respect language-specific collation rules.
> This would probably involve changing at least the
> [NodeUtils.compareLiteralsBySyntax|https://github.com/apache/jena/blob/master/jena-arq/src/main/java/org/apache/jena/sparql/util/NodeUtils.java#L199]
> method.
> It currently sorts by lexical value first, then by language tag. Since the
> collation order needs to be stable across all possible literal values, I
> think the safest way would be to sort by language tag first, then by lexical
> value according to the collation rules for that language.
> But what about subtags like {{@en-US}} or {{@pt-BR}}? Can they have different
> collation rules than the main language? It would be a bit strange if all
> {{@en-US}} literals sorted after {{@en}} literals...
> It would be good to check how Dydra does this and possibly take the same
> approach. See the message linked above for further backgound.
> I've been talking with [~kinow] about this and he may be interested in
> implementing it.
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