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Re: Storing RDF in relational databases

From: Alexander V. Besprozvannykh <alexander@meteo.ru>
Date: Sun, 14 Nov 1999 21:34:33 +0300
Message-ID: <006f01bf2ece$ea2e5970$4dc5b2c3@meteo.ru>
To: "Sergey Melnik" <melnik@DB.Stanford.EDU>, "RDF Interest Group" <www-rdf-interest@w3.org>
Cc: <eric@tux.w3c.org>
Dear Sergey.
I am developing enterprise information system with relational database using
Internet technologies.
One of main solution is XML and DRF. I am using RDF as XML sublanguage to
present metadata about of all resources of the system (external and
internal). XML RDF serialization is used only for transmit data over
Internet or Intranet. The object model of RDF is triples (not DOM XML as for
other data) in TripleStore object with useful methods.
In this case we need:
- translation RDF to triples;
- translation triples to RDF;
- storing triples into relational database;
- retrieving requested triples from database to object model;
- RDF Query Language schema;
- translator from RDF query to SQL.
We can save triples in relational database exactly as triples in object
model.
/*                 Triples Table Definition*/
CREATE TABLE  Triples
(
Subject             VARCHAR2(256),
Predicate           VARCHAR2(256),
Object              VARCHAR2(256),
UNIQUE(Predicate,Subject)
);

But I do not use expanded XML namespaces in database and use abbreviated
form (rdf:type) and table for schema definition ("rdf",
"http://www.w3.org/1999/02/22-rdf-syntax-ns#"). In this case I can load from
database any resource description and produce RDF file by using Servlet
technology for instants. If I don't use RDF Query Language I can make
reference to RDF from Web page:
http://www.host.com:8080/servlet/rdf /resource-name and display it using
XSL. If I need some metadata from software I can produce request using DRF
Query language to select information that I need. This technology was tested
by me, but I have some questions:
- what happened if I will have many records in database (productivity);
- I have not standard for RDF Query Language.

Best regards, Alexander V. Besprozvannykh.
alexander@meteo.ru


----- Original Message -----
From: Sergey Melnik <melnik@DB.Stanford.EDU>
To: RDF Interest Group <www-rdf-interest@w3.org>
Cc: <eric@tux.w3c.org>
Sent: Saturday, November 13, 1999 10:51 AM
Subject: Storing RDF in relational databases


> To have a common way to refer to different approaches to storing RDF in
> relational databases I compiled a brief summary of what is known to me
> and made it accessible under
>
> http://www-db.stanford.edu/~melnik/rdf/db.html
>
> If you have implemented or thought of a solution for management of RDF
> data using the relational database technology, please contribute your
> ideas to this list. I'll try to reflect them on the above page. To goal
> is to come up with the best way of storing RDF in a relational database,
> or identify a set of solutions suitable for particular needs.
>
> Sergey
>
Received on Sunday, 14 November 1999 13:36:34 GMT

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