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RE: RDF storage

• To: "Chiusano Joseph" <chiusano_joseph@b...>
• Subject: RE: RDF storage
• From: "Howard Katz" <howardk@f...>
• Date: Mon, 17 May 2004 12:18:44 -0700
• Cc: "Joshua Allen" <joshuaa@m...>,"John Song" <sq02@k...>,"Xml-dev" <xml-dev@l...>
• Importance: Normal
• In-reply-to: <40A90D24.67DB0107@b...>

Ah heck, doesn't matter. I'll happily disagree with whoever's talking!

No seriously, red-faced here. Sorry about that.

Howard

> -----Original Message-----
> From: Chiusano Joseph [mailto:chiusano_joseph@b...]
> Sent: Monday, May 17, 2004 12:06 PM
> To: Howard Katz
> Cc: Joshua Allen; John Song; Xml-dev
> Subject: Re:  RDF storage
>
>
> I think you meant to refer to Joshua :)
>
> Kind Regards,
> Joe Chiusano
> Booz | Allen | Hamilton
> Strategy and Technology Consultants to the World
>
> Howard Katz wrote:
> >
> > I don't know if I agree with that assessment, Joseph, at least regarding
> > relational tables. I haven't done much implementation work myself, other
> > than munging my own XQuery engine to provide a native internal
> format for
> > RDF triples, but my impression is that it's not that difficult
> to implement
> > a backend store for RDF in a relational table. Each triple
> ultimately just
> > boils down to three integer columns, which are either pointers
> into tables
> > of indexed URIs or literal data instances. I've been looking at doing
> > exactly that with my own engine: implementing an optional
> SQL-based backend
> > as a user option, and at first glance it doesn't look that difficult.
> >
> > Does anybody on the list have contrary experience? I know at least a few
> > members of the RDF Data Access Working Group have implemented
> backends in
> > SQL. I was quite intrigued to look over a few shoulders at the last
> > face-to-face meeting of the group and watch people hacking away on big
> > repositories in MySQL.
> >
> > I agree that implementing via a native XML database doesn't buy
> you much,
> > other that the ability to easily [expletive deleted] in RDF that's been stored
> as RDF/XML
> > and to serialize to the same format on output. That's
> definitely extremely
> > useful for interop. However there's too big an impedance
> mismatch between
> > the sort of things you'd like to do with XML and with RDF to
> buy you much of
> > value on the query side.
> >
> > Best,
> > Howard
> >
> > > -----Original Message-----
> > > From: Joshua Allen [mailto:joshuaa@m...]
> > > Sent: Monday, May 17, 2004 11:12 AM
> > > To: John Song; Xml-dev
> > > Subject: RE:  RDF storage
> > >
> > >
> > > >   and the arising problems? the most difference betwwen RDF
> > > > and pure XML is the data model which is hierarchical tree for XML
> > > >   and graph for RDF.so if storing RDF in NXD,maybe it is
> > > > needed to redesign the storage model and also mapping rdf query
> > > >   like RQL into XML query language like XQuery.
> > > >   It seems that the most appealing thing to store RDF in NXD
> > > > is that i can utilize the index and other optimizing
> > >
> > > You are correct; the difference in data model makes it
> difficult to get
> > > any advantage from Xquery.  The same applies to indexing though.  The
> > > idices which are supported by native XML databases are not RDF-aware.
> > > However, we could make the same criticism of relational
> databases -- the
> > > RDF data model is not at all like the relational data model;
> so vendors
> > > have been forced to implement custom indexing and query schemes atop
> > > relational engines.  Since it requires a lot of custom work
> either way,
> > > I do not think that either relational or native-XML have a distinct
> > > advantage over the other, except for the fact that relational engines
> > > are more mature, and targeting relational makes it easier to
> port a RDF
> > > engine to multiple platforms.  A native XML database would
> perhaps have
> > > an easier time preserving the full fidelity of the input RDF
> documents,
> > > but it is also possible for a relational-backed engine to store the
> > > source RDF in a CLOB when shredding the RDF to relational tables.
> > >
> > > -----------------------------------------------------------------
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> >
> > -----------------------------------------------------------------
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> >
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> >
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>
> --
> Kind Regards,
> Joseph Chiusano
> Associate
> Booz | Allen | Hamilton

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  • Re: RDF storage
    • From: "Chiusano Joseph" <chiusano_joseph@b...>

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