W3C home > Mailing lists > Public > www-rdf-interest@w3.org > March 2004

Re: Storing RDF in a relational database

From: Eric Jain <Eric.Jain@isb-sib.ch>
Date: Wed, 31 Mar 2004 18:20:46 +0200
Message-ID: <015901c4173c$1f5d95c0$c300000a@caliente>
To: "Dave Beckett" <dave.beckett@bristol.ac.uk>
Cc: "rdf-interest" <www-rdf-interest@w3.org>

> With respect to your schema - order of triples seems unimportant in
> rdf apps I've built.

I think it's a bit like the icons on your desktop. It doesn't really
matter where they are placed (certainly the file system doesn't care),
but it sure is annoying if they are regularly rearranged randomly :-)


> You support only a small set of possible datatypes.

The idea is that having columns for string, float and boolean values
should be enough for answering most queries, as most datatypes can be
efficiently mapped to one of those three types. On the other hand, a
column that stores the actual datatype should probably be included, as
soon as I get over the fact that with RDF you need to explicitly specify
data types in your instance data.


> I'm not sure whether namespaces as you describe them
> makes things faster or more complex in queries and storage.

Not sure I follow you. Storing namespaces inline would increase storage
space and slow down things considerably (unless your database supports
bitmap indexes), and I don't think anyone does that?


> The choice
> to have reification also can make SQL queries harder to construct.

The only alternative I am aware of would be to explicitly store reified
statements, but this is not a practical solution in our case as we make
heavy use of reification.


> It sounds like you have some big iron running that database?

Absolutely not. As pointed out, storage and retrieval is really
efficient. However, if we wanted to make the querying facilities
publicly available, there would indeed be the need for some very big
iron, or at least lots of small irons :-)
Received on Wednesday, 31 March 2004 11:21:56 UTC

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