Re: Evaluation of multiple SERVICE clauses on Virtuoso

On Feb 27, 2018, at 12:06 PM, Franck Michel <franck.michel@cnrs.fr> wrote:
> 
> Dear all,
> 
> I'm noticed that Virtuoso adopts what I believe to be a very inefficient strategy to evaluate a SPARQL query containing multiple SERVICE clauses with independent graph patterns (no common variable): each SERVICE clause is invoked once for each solution retrieved from previously evaluated SERVICE clauses.
> 
> This ends up in a very inefficient multiplication of SERVICE invocations, although they return the same results each time (since the graph patterns are independent).
> 
> Has any of you already noticed this behaviour? Would you say this is a bug or is there a good reason that I don't catch?
> 
> I wanted to post this on a Virtuoso forum but all the URLs I've found are dead. I you have a pointer, I would appreciate it.
> 
> Thanks for your help.
> 
> Note: I'm using the OS edition 7.20.
> 
> -- 
>   
> Franck MICHEL
> CNRS research engineer
> +33 (0)492 96 5004
> franck.michel@cnrs.fr <mailto:franck.michel@cnrs.fr>
>  
> Université Côte d’Azur, CNRS - I3S - UMR 7271
> 930 route des Colles - Bât. Les Templiers
> BP 145 - 06903 Sophia Antipolis CEDEX - France
> Tel. +33 (0)4 9294 2680, Fax : +33 (0)4 9294 2898 
> 



Hello, Franck --

I'm surprised every forum URL you found related to Virtuoso was 
dead, though of course systems and services do change over time, 
and links sometimes succomb to bitrot.

I would also appreciate being alerted (optimally, off-list) to 
any particular links you've found to be dead, so we can do what 
we can to ensure that people who encounter those links in the 
wild still get through to us.

I'll provide a few links to current Virtuoso resources below,
to hopefully help others in future.

To start with, OpenLink Software, producer of Virtuoso (and my
employer), is alive and well, and has been throughout, with our
main website at --

   https://www.openlinksw.com/

The main Virtuoso info site, for both Open Source and Enterprise
Editions, is the same as it always has been --

   https://virtuoso.openlinksw.com/

-- and the product manual remains at --

   http://docs.openlinksw.com/

The Virtuoso Open Source project started on SourceForge, and 
as Hugh and Ghislain suggested, all mailing lists found there 
(virtuoso-announce, virtuoso-devel, virtuoso-distros, and 
virtuoso-users) remain active --

   https://sourceforge.net/p/virtuoso/mailman/

Bugs and other issues found with the Open Source project are
generally best raised on the current github project --

   https://github.com/openlink/virtuoso-opensource/issues

Our main Support Center and Case System is also available for 
bug reports on Open Source (especially where confidentiality is 
important), and more generalized help for users of Commercial 
Edition and support subscribers using either Edition.

   http://support.openlinksw.com/support/online-support.vsp

We also actively monitor a number of public forums, both special 
interest and multi-topic, with most action currently seen on 
Stack Overflow.  Be sure to appropriately tag your questions 
with Virtuoso, SPARQL, RDF, DBpedia, etc.

I hope this is helpful.

Ted




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Ted Thibodeau, Jr.           //               voice +1-781-273-0900 x32
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