Re: ISSUE-3

Hello Angela:
Just to be clear, you are speaking about multiple relational databases, 
right?
If so, several existing tools solve that problem.  I will let the owners 
of the tools
speak for themselves.

If you are talking about a mixture of relational and non-relational 
databases, then that
is a more difficult problem.  I don't think our work on the WG will 
address that.
All the best, Ashok


Fogarolli Angela wrote:
> Hi all,
> I am new to the group so I don't know if I understood correctly the
> previous work done by the group and the objectives. I would like to
> ask some questions for clarifying a couple of points related to the
> issue came up during the last conference call which is about the
> Mapping Language we should deliver.
> I apologize if I am misunderstood or if this is not focused on the
> objectives of the group.
> I am currently leading a data integration project at the instance
> level using the OKKAM infrastructure. We were thinking to use D2R for
> avoiding the implementation of a big KB.
> A big issue I see also in this experience is the necessity to run
> queries on multiple data sources.
> From the project presentations we listened to till now it emerged that
> we are able to map databases to RDF but we are not able to connect
> them so we are not able to run queries which span multiple databases
> (please, tell me if I am wrong...I am not an expert, just trying to
> clarify to myself some ideas in order to be helpful in the future).
> I was thinking that since it's possible to decompose queries using
> relational algebra and this mapping should be an objective of this
> group (?) then the same mapping could be used to understand to which
> database (or sparql endpoint) to send a piece of query.
> I am not sure that this problem is part of the objectives of this
> group, even though I think that the data integration issue should be
> addressed, as written in the W3C RDB2RDF Incubator Group Report
> http://www.w3.org/2005/Incubator/rdb2rdf/XGR-rdb2rdf/  (point 1.1.3
> Integration of Enterprise Information Systems)
> My question is:
> Could the mapping delivered by this group also solve (or provide a way
> to solve) the problem of the sparql federated queries ? I think this
> will be extremely important for implemented the linked data idea.
> In my point of view once we have created a mapping from sparql to sql
> then this can also be re-used for implemented federated queries.
>
> Thanks in advance.
> Angela
>
> On Thu, Nov 12, 2009 at 2:33 PM, ashok malhotra
> <ashok.malhotra@oracle.com> wrote:
>   
>> Hello Ahmed:
>> I envision that the work of the WG is one-way: from RDB to RDF/OWL.
>> So, to answer your question, I do not envision creating SQL tables in the
>> RDBMS from SPARQL application using R2RML.
>> All the best, Ashok
>>
>>
>> Ezzat, Ahmed wrote:
>>     
>>> Hi Ashok,
>>>
>>> Thanks for the follow up. I agree with your clarification regarding the
>>> mapping SPARQL to SQL is out of scope; having discussion about it if the
>>> team want to pursue is fine - I am trying to separate what we discuss, with
>>> time constraints, from what we will commit to deliver which we need to pin
>>> down early 2010.
>>>
>>> I liked the D2R presentation scope in the mapping area; is reasonable.
>>>
>>> Regarding DDL statements mapping support: do you envision creating SQL
>>> tables in the RDBMS from SPARQL application using R2RML or do you envision
>>> the ability through the R2RML to read the different schema objects
>>> definitions in the RDBMS from a SPARQL application?  I agree that the latter
>>> is a must and would be interested in getting your input as well as others on
>>> the first.
>>> Regards,
>>>
>>> Ahmed
>>>
>>>
>>> -----Original Message-----
>>> From: public-rdb2rdf-wg-request@w3.org
>>> [mailto:public-rdb2rdf-wg-request@w3.org] On Behalf Of ashok malhotra
>>> Sent: Wednesday, November 11, 2009 13:58
>>> To: RDB2RDF WG
>>> Subject: ISSUE-3
>>>
>>> Since the goal of the WG is to create a mapping from RDB Schemas to
>>> RDF/OWL classes, perhaps
>>> we should rephrase the bullet point in the requirements as
>>>
>>>    * The mapping language MUST define the set of SQL DDL
>>>      to be supported in the first release. The set to be supported
>>>      SHOULD be as complete as possible and be defined as soon as
>>>      possible after the WG official launch.
>>>
>>> This will let us exclude Table Types if we wish.
>>>
>>> I apologize that the original bullet was interpreted to mean that the the
>>> WG should define
>>> a mapping from SPARQL to SQL.  That was not the intention.  In my view,
>>> the mapping of
>>> SPARQL to SQL should be left open as a technology on which various
>>> implementations
>>> can compete. .
>>>
>>>

Received on Thursday, 12 November 2009 15:53:57 UTC