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https://issues.apache.org/jira/browse/JENA-1313?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15955146#comment-15955146
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Osma Suominen commented on JENA-1313:
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[~andy.seaborne] Thanks for the clarification. I think that using comparators
instead of collation keys would be the right way then. That's also what the ICU
documentation recommends, unless you have a huge amount of data or are going to
store the keys in some kind of a database. At least ICU claims that their
comparators are clever (they avoid doing unnecessary work) and thus fast. I
would expect the Java standard library collation to do the same.
So how do we move on from here? My original use case is still valid, I just
want a way to perform ORDER BY on literals using language-specific collation
rules.
1. Change the default sorting behavior? (perhaps controlled by an ARQ setting
to toggle "locale mode")
2. Implement a {{collate:collate}} function - but not exactly the way I
proposed, since that would be inefficient
3. Implement an ARQ extension for ORDER BY, e.g. WITH <comparator>
> 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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