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Re: Fwd: Looking for the right RDF store(s)

From: Markus Krötzsch <markus.kroetzsch@comlab.ox.ac.uk>
Date: Fri, 25 Feb 2011 20:56:09 +0000
Message-ID: <4D681769.4090400@comlab.ox.ac.uk>
To: Atanas Kiryakov <naso@sirma.bg>
CC: semantic-web@w3.org, "OWLIM-info@ontotext.com" <OWLIM-info@ontotext.com>
On 25/02/2011 17:40, Atanas Kiryakov wrote:
> Dear Markus,
>
> my second round of comments follow inline

Thanks, these clarifications were helpful.

Just one question:

<snip>

>>
>> We would be happy with interval restrictions on number and string data.
>
> At present we do not perform number normalisation and special purpose
> indexing. Thus, comparing number literals is done based on their string
> representation. Thus, if one needs to do accurate interval searches and
> other constraints on numbers, s/he should take care to normalise the
> string representation of the numbers in the application. Still,
> performance-wise doing such types of constraints on literals is fast
> enough for usage scenarios we have seen so far

If by normalisation you mean the transformation into the canonical XSD 
representation, then I do not quite see how lexicographic ordering would 
give you the same results as numerical ordering. In particular, leading 
zeros are prohibited in canonical number formats, so numbers 1, 2, 10 
would really yield the strings "1", "2" and "10" which would sort 
lexicographically as "1" < "10" < "2".

But in general we would compute the canonical forms of all data anyway 
before pushing it to any store, so this is not a problem.

- Markus

-- 
Dr. Markus Krötzsch
Oxford  University  Computing  Laboratory
Room 306, Parks Road, Oxford, OX1 3QD, UK
+44 (0)1865 283529    http://korrekt.org/
Received on Friday, 25 February 2011 20:59:50 GMT

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