On 10/11/12 11:18 AM, John F Sowa wrote:
> KI
>> >see also:
>> >
>> >http://bit.ly/UnOpac -- LInkedWiki Demos (basically MediaWiki +
>> >Semantic MediaWiki + LinkedWiki extensions deployed via Virtuoso...
>> >enhanced via use of SPARQL instead of SQL
> But note that most vendors of triple stores support SQL as an option
> for complex queries. (01)
Not disputing that, we do that. But one has to be careful about what
"complex" implies. For instance, we support SPARQL, SPASQL (sparql
inside sql), and SQL. Each has its own virtues re. complexity handling. (02)
> I noticed that none of the examples on that page
> use the SPARQL operators FILTER, OPT, or UNION. (03)
That's me trying to keep it simple. (04)
I can make pages with those operators that will hit a 50 Billion+ live
instance of Virtuoso. We are bringing that online as a replacement of
the older LOD cloud cache which would handle any of the aforementioned
operators against a 29 Billion+ instance. (05)
> If SPARQL is going
> to survive for the long term, it will have to replace them with the
> SQL operators: AND, OR, NOT, and EXISTS. (06)
We implemented that a long time ago. (07)
As I am sure you know, these also affect the ability to performed
backward-chained inference at the aforementioned scales. I've
demonstrated these things for years via our live LOD cloud cache instances. (08)
>
> People understand AND, OR, NOT, and EXISTS -- and their combinations.
> They can be evaluated in polynomial time in all SQL implementations.
> But nobody, not even the SPARQL developers, understand FILTER, OPT,
> and UNION. (09)
As per my comments above, we do, and we always opt to demonstrate our
understanding via live instances of Virtuoso. (010)
> They're still publishing papers to show that combining
> them makes the evaluation NP complete. (011)
Well, we have a feature called "Anytime Query". If leverages partial
results sets and dynamic cursors at massive scales. That's what we can
produce faceted browsing front-ends in HTML that enable
multi-dimensional exploration of Linked Data style of entity
relationship graphs. (012)
Links: (013)
1. http://bit.ly/ONYFDH -- Google Spreadsheet with some benchmark
results for the Virtuoso hybrid DBMS engine . (014)
-- (015)
Regards, (016)
Kingsley Idehen
Founder & CEO
OpenLink Software
Company Web: http://www.openlinksw.com
Personal Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca handle: @kidehen
Google+ Profile: https://plus.google.com/112399767740508618350/about
LinkedIn Profile: http://www.linkedin.com/in/kidehen (017)
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