On 10/29/13 1:32 PM, John F Sowa wrote:
> b) SQL was designed for a database organized as tables stored on
> local disks. SQL systems optimize queries by compiling them
> to a more efficient form (with methods similar to those that
> Prolog programmers routinely use to optimize their code).
>
> c) SPARQL was designed for accessing data located in documents
> on the Internet. The access times can be much worse than a
> local disk, not to mention RAM. The indexing and optimization
> of SQL and Prolog is, in general, not possible. (01)
SQL and SPARQL aren't as dissimilar as some might assume, in reading
your comments above. (02)
SQL Tables are Documents comprised of records. (03)
RDF Documents are (as you know anyway) comprised propositional statements. (04)
SQL struggles with federation because Tables are local and DBMS engine
specific. (05)
SPARQL does much better with federation because each propositional
statement is comprised of subject (entity), predicate (attribute), and
object (value) that can be denoted using an HTTP URI, unlike SQL where
identifiers are typically DBMS engine specific. In short, federation is
natural when dealing with SPARQL. (06)
To conclude, bearing in mind I accept the poor documentation that swirls
around RDF and SPARQL can be confusing++, the optimizations that you
align re. SQL and Prolog apply equally to SPARQL. (07)
As for federation, as I stated earlier, that's another example of where
SPARQL trumps SQL in a really big way :-) (08)
-- (09)
Regards, (010)
Kingsley Idehen
Founder & CEO
OpenLink Software
Company Web: http://www.openlinksw.com
Personal Weblog: http://www.openlinksw.com/blog/~kidehen
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LinkedIn Profile: http://www.linkedin.com/in/kidehen (011)
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