Re: [Bigdata-developers] TupleQuery vs. ParsedQuery

[Jerven T. B. <Jer...@si...>]

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.

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 ;)


Regarding the openrdf parser questions you can ask them at eclipse-rdf4j 
https://groups.google.com/forum/#!forum/rdf4j-users

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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-- 
Jerven Tjalling Bolleman
SIB | Swiss Institute of Bioinformatics
CMU - 1, rue Michel Servet - 1211 Geneva 4
t: +41 22 379 58 85 - f: +41 22 379 58 58
Jer...@si... - http://www.sib.swiss