Re: TPF and DBMSes (was Re: Hydra and Shapes)

On 11/22/14 3:46 PM, Kjetil Kjernsmo wrote:
>
> On Friday 21. November 2014 13.44.02 Kingsley Idehen wrote:
>
> > To be more precise, since I don't like DBMS and Database Document
>
> > conflation either, A SPARQL processor needs a mechanism for targeting
>
> > database documents.
>
> >
>
> > In the case of
>
> > <http://client.linkeddatafragments.org/#sparql-processor>, how does
>
> > handle what I've outlined above work?
>
> As they said, it is just the UI, you can hand any TPF data source to 
> the client and off you go.
>
> But I think that misses the crucial point, which is how things happen 
> behind that. Strictly, Ruben is right; you can basically materialize 
> all possible triple patterns, with pages, and store them in a file 
> system. In that case, it is correct that no DBMS is involved.
>
> However, I would claim that this is not practical in almost all cases. 
> I have myself been working on a system that did something similar, in 
> a fairly high-traffic, but slow-update case, which is the case where 
> it possibly makes most sense, but the horror of the code we had to 
> manage the updates, I still shiver at the thought! :-) Essentially, it 
> is writing YA materialization framework.
>
> I think you'd much rather like to ensure that you have a good DBMS at 
> the bottom, then a layer that serves TPFs, and makes sure you have 
> cache headers, and then a reverse caching proxy facing the network 
> (which is about the architecture that I'm running on my endpoint).
>
> However, this places three requirements that aren't necessarily easy 
> on the DBMS. The first, that I know that you do well, already, 
> Kingsley, is paging. The next is that it must be much cheaper to 
> compute the cardinality (or at least an estimate) of any triple 
> pattern result, than computing the result of the same triple pattern. 
> Can you do that with Virtuoso? If yes, how do we access it?
>

We can make it accessible via metadata. As you can see in our Faceted 
Browser Pages, we return information about cost of query, pages etc.. 
I'll get what's shown in the footer 100% mirrored via metadata (using 
<link/> and "Link:" for different kinds of user agent level exploitation).

-- 
Regards,

Kingsley Idehen	
Founder & CEO
OpenLink Software
Company Web: http://www.openlinksw.com
Personal Weblog 1: http://kidehen.blogspot.com
Personal Weblog 2: http://www.openlinksw.com/blog/~kidehen
Twitter Profile: https://twitter.com/kidehen
Google+ Profile: https://plus.google.com/+KingsleyIdehen/about
LinkedIn Profile: http://www.linkedin.com/in/kidehen
Personal WebID: http://kingsley.idehen.net/dataspace/person/kidehen#this