W3C home > Mailing lists > Public > www-rdf-interest@w3.org > May 2002

Query and storage

From: Seaborne, Andy <Andy_Seaborne@hplb.hpl.hp.com>
Date: Thu, 23 May 2002 11:53:55 +0100
Message-ID: <5E13A1874524D411A876006008CD059F038D38B7@0-mail-1.hpl.hp.com>
To: "'Graham Klyne'" <GK@ninebynine.org>
Cc: www-rdf-interest@w3.org
Graham wrote:

> As someone who has recently designed and implemented a (yet another) RDF 
> query "language", I'm not convinced we're ready to standardize.  I'm not 
> convinced we know enough about the performance issues in RDF, and I'm also

> not convinced that standardizing a query language at this time would bring

> great benefits.  But I could be wrong on both counts.

> My own intuition is that a query language for RDF should aim to operate at

> a higher level than "find this pattern of triples", but in my 
> implementation it was hard to break away from.  I'd like to see more work 
> on storage formats before we nail down a query language.

Graham,

> a higher level than "find this pattern of triples"

Agreed.  There are two problems that are closely related by sharing
technology but are different use models.  Query-variable bindings is a
matter of one layer of the application wanting to ask questions of the RDF
graph ("find the resource such that ...") and the extract subgraph that is a
matter of RDF->RDF transformation by restricting one graph.  These two seem
to get mixed up.

> I'd like to see more work on storage formats before we nail down a query
language.

This is where I disagree: I don't want to see a relationship between the
query language and the storage.  I think query should be specified in
relation to the RDF graph.  It would be different implementations for
different application domains that make decisions about storage and query
*implementation*.  There is no need to bind storage choices to QL choices.

	Andy
Received on Thursday, 23 May 2002 06:54:06 GMT

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