Re: [Bigdata-developers] TupleQuery vs. ParsedQuery

[Adrian B. <Adr...@ma...>]

Hi Artem,

thanks for the reply.

On 12/01/17 19:38, Artem Kozlov wrote:
> Hi Adrian,
>
> Query that you are trying to parse is not a valid SPARQL query - "The
> variable introduced by the |BIND |clause must not have been used in
> the group graph pattern up to the point of use in |BIND|.
> " [https://www.w3.org/TR/sparql11-query/#bind] .
I would have thought so too, but not only does blazegraph accept it (at
least as a TupleQuery-Object) but if I execute it in query.wikidata.org
(which uses blazegraph as a backend) it runs successfully.
Interesstingly enough the result is the same as

SELECT DISTINCT ?item
WHERE
{ BIND (wd:Q146 AS ?tree0)
?tree0 wdt:P31 ?item}
>
> Regards,
>
> Artem
>
> On Wed, Jan 11, 2017 at 3:15 PM, Adrian Bielefeldt
> <Adr...@ma...
> <mailto:Adr...@ma...>> wrote:
>
>     Hello everyone,
>
>     I'm writign on behalf of a Wikidata Research Project
>     <https://meta.wikimedia.org/wiki/Research:Understanding_Wikidata_Queries>
>     into SPARQL-Queries. We are writing a java application to parse
>     SPARQL-Queries from the query.wikidata.org-logs and analyse them
>     for different features. At the moment we are parsing the queries with
>     org.openrdf.query.parser.QueryParserUtil into
>     org.openrdf.query.parser.ParsedQuery-Objects. Unfortunatly we
>     cannot parse queries like this one:
>
>     SELECT DISTINCT ?item
>     WHERE
>     { ?tree0 wdt:P31 ?item . BIND (wd:Q146 AS ?tree0) }
>
>     because of: "BIND clause alias '{}' was previously used".
>
>     If we parse them as org.openrdf.query.TupleQuery-Objects using
>     org.openrdf.repository.RepositoryConnection.prepareTupleQuery they
>     are parsed just fine.
>
>     Unfortunatly, the TupleQuery-Objects do not support the
>     analysis-Features of ParsedQuery.
>
>     All of which leads to 2-3 questions:
>
>     1. Why is this kind of query accepted by one parser but not the other?
>     2. Is it possible to obtain a ParsedQuery-Object from a
>     TupleQuery-Object?
>     (3. Is this the right mailing list to post these questions to?)
>
>     Greetings,
>
>     Adrian Bielefeldt
>
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