On 12 Nov 2009, at 16:26, Ezzat, Ahmed wrote:
> Given that the goal of the WG is to create a mapping from RDB  
> Schemas to RDF/OWL classes only.  This require us to be able to read  
> the schema but not necessarily to modify it.

+1 for scoping this WG to read-only access.

> This leads me: R2RML mapping language MUST support as complete as  
> possible all SQL data and object types and any exceptions will be  
> identified as soon as possible after the WG launch.

+1 for supporting as many SQL data types as possible. But what's the  
target for "all" data types? Does this include, say, the XML type of  
SQL:2003? What about types that are not in the standard but commonly  
used in popular RDBMS? I don't even know if SQL:2008 adds any new  

Are you saying that user-defined object types should be supported in  
the language? I'm opposed to that idea. My impression is that this is  
implemented very inconsistently across different RDBMS, if at all; it  
adds a lot of complexity to the already big overall task of the WG;  
I'm not aware of any existing RDB2RDF system that handles them from  
which we could learn, so we move from standardisation into research  
territory; I would have no idea how methods with arguments should be  
handled; and only a small minority of RDBMS users seem to be using  
user-defined object types. So from my POV the case for including them  
is weak; certainly not good enough for a MUST at this stage.


> All, does the above capture what the goal is.
> Feel free to edit/agree/disagree, etc..
> Regards,
> Ahmed
> -----Original Message-----
> From: ashok malhotra []
> Sent: Thursday, November 12, 2009 05:34
> To: Ezzat, Ahmed
> Subject: Re: ISSUE-3
> 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: [ 
>> ] On Behalf Of ashok malhotra
>> Sent: Wednesday, November 11, 2009 13:58
>> 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 22:23:47 UTC