On 1 Dec 2010, at 10:54, Diogo FC Patrao wrote: > I thought of using oracle-xe and dblinks to federate the RDBS. does > d2rq > allows a table to be called, say, "ext_db.ext_ta...@my_link"?
I have no idea! But if that's a valid table name in Oracle, then D2RQ should allow it, and if it doesn't at the moment then I'll fix it. Richard > > > Diogo F.C. Patrão > Manager of Medical Informatics > Biotechnology Laboratory > Hospital A.C. Camargo > http://www.accamargo.org.br/ > > > On Wed, Dec 1, 2010 at 8:11 AM, Diogo FC Patrao > <[email protected]>wrote: > >> Hello Richard >> >> As for the practical needs I have, ETL seems the way to go, >> unfortunately. >> But I found a good tool (Pentaho community - download it at >> sourceforge) >> that seems very good to design and keep such a repository running. >> >> We're starting today a study group on d2rq source to try to >> contribute with >> d2rq, in the sense of fully supporting multiple databases >> connection by >> keeping queries over them separated. Could you suggest some >> starting point >> for us to begin with? >> >> Thanks! >> >> Diogo F.C. Patrão >> Manager of Medical Informatics >> Biotechnology Laboratory >> Hospital A.C. Camargo >> http://www.accamargo.org.br/ >> >> >> On Wed, Dec 1, 2010 at 7:53 AM, Richard Cyganiak >> <[email protected]>wrote: >> >>> On 29 Nov 2010, at 14:13, Diogo FC Patrao wrote: >>> >>>> The rewriting engine is not designed to work with multiple DBs, so >>>>> sometimes it works by accident, but in general it won't. >>>>> >>>> >>>> Do you think that if we configure the query rewriting module to >>>> not JOIN >>>> databases, that would work? >>>> >>> >>> The easiest way of achieving this is running multiple instances of >>> D2R >>> Server. >>> >>> >>> It would certainly be great if D2RQ had that ability. It's an open >>>>> source project and contributions are always welcome ... >>>>> >>>> >>>> That's definitely something I'm interested into, and would gladly >>>> give >>>> some >>>> of my employee's time to solve. Do you have an idea how exactly >>>> to solve >>>> this? Contact me in pvt if you wish. >>>> >>> >>> This goes into the direction of federated SPARQL queries. There is >>> quite a >>> bit of research already out there, but I don't think that any really >>> practical solution has been described in the literature yet, so >>> solving this >>> likely requires a fair bit of original research. >>> >>> >>> Anyways, if you want to integrate several data stores, at this point >>>>> I'd recommend either using the basic federated query feature of >>>>> Andy >>>>> Seaborne's ARQ, or Extract-Transfer-Load them all into one >>>>> triple store. >>>>> >>>> >>>> you mean this ? http://jena.sourceforge.net/ARQ/service.html >>>> >>>> So I would have several instances on D2R-Server mapping different >>>> databases >>>> to the same ontology, then query them with ARQ using this SERVICE >>>> statement? >>>> >>> >>> Yes. As stated on this page, it doesn't do any smart query >>> planning, so >>> essentially you have to do the query planning yourself when >>> writing the >>> query, but at least you can get results. See also: >>> >>> http://seaborne.blogspot.com/2007/07/basic-federated-sparql-query.html >>> http://www.w3.org/2009/sparql/docs/fed/service (just a draft, I >>> think >>> it's not being further pursued by the working group at this point) >>> >>> Best, >>> Richard >>> >>> >>> >>> >>>> ETL is not the ideal for me, I have several production databases >>>> I want >>>> to >>>> integrate, and I would avoid dealing with DW updates. >>>> >>>> Thanks, >>>> >>>> dfcp >>>> >>>> >>>> >>>> >>>>> Best, >>>>> Richard >>>>> >>>>> >>>>> >>>>>> Regards >>>>>> Dr Christian Brenninkmeijer >>>>>> University of Manchester >>>>>> >>>>>> >>>>>> ------------------------------------------------------------------------------ >>>>> >>>>>> Increase Visibility of Your 3D Game App & Earn a Chance To Win >>>>>> $500! >>>>>> Tap into the largest installed PC base & get more eyes on your >>>>>> game by >>>>>> optimizing for Intel(R) Graphics Technology. 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