Re: [Bigdata-developers] TupleQuery vs. ParsedQuery

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

Hi Jerven,

thanks for the reply.

On 12/01/17 10:03, Jerven Tjalling Bolleman wrote:
> Hi Adrian,
>
> I am not involved in BigData/BlazeGraph etc.. but I can provide some
> insight.
>
> On 2017-01-11 15:15, Adrian Bielefeldt wrote:
>> I'm writign on behalf of a Wikidata Research Project [1] 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.
>
> This is practically an invalid SPARQL query (different systems accept
> more or less) but
> the query is nonsensical. The Query Parser reports that.
> The TupleQuery parses according to the AST which does not "judge" a
> query on its merits.
>
So what you're saying is that the TupleQuery-Object creates the AST but
does not notice that there is actually no sensible way to execute it?
Then what happens if I call .evaluate() on this object?
> It has been a while since I did any query analysis for
> sparql.uniprot.org.
> What I did at that time is for more detailed analysis is use the
> SPIN-API [2] to convert
> the SPARQL query string to an RDF representation. Loaded that SPARQL
> query as RDF into a
> triple store and used SPARQL to analyze those SPARQL queries. i.e. use
> SPARQL to analyze analytical SPARQL queries ;)
>
We thought about that as well. Is there some kind of public project
documentation on this? It would certainly be of interest to us.
> Regarding the openrdf parser questions you can ask them at
> eclipse-rdf4j https://groups.google.com/forum/#!forum/rdf4j-users
>
Thanks, I'll try it there too.
> rdf4j at eclipse is what was formerly named openrdf/sesame.
>
> Regards,
> Jerven
>
> [2] https://github.com/spinrdf/spinrdf/
>
>>
>>
>> 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
>>
>>
>> Links:
>> ------
>> [1]
>> https://meta.wikimedia.org/wiki/Research:Understanding_Wikidata_Queries
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>