classes which satisfy graph pattern with reasoning turned off are not returned with reasoning on

[steve....@vanderbilt.edu]

This problem is described in the "Breaking Stardog" section of http://baskauf.blogspot.com/2016/02/stress-testing-stardog-reasoner.html

The test I ran involved loading the files in https://github.com/baskaufs/Bioimages/blob/master/bioimages-rdf.zip .  The file dsw.owl was loaded as a named graph that was specified as the Tbox.  The other files were loaded in the default graph.

I ran the query 

SELECT DISTINCT ?class
WHERE {
  ?occurrence dsw:hasEvidence ?token.
  ?token a ?class.
  ?occurrence dsw:atEvent ?event.
  ?event dsw:locatedAt ?location.
  ?location dwc:countryCode "US".
}

without reasoning turned on and it quickly returned the correct classes:

dcmitype:StillImage
dwc:PreservedSpecimen

With reasoning turned on, the first time I ran the query, it timed out. On subsequent attempts, the query took 12 minutes to complete, but no results were returned.  At a minimum, the same classes should be returned as before, but the results should also include the class 

dsw:Token

which is entailed by use of a predicate with a range declaration.  There was no error message or timeout message given that I could see.

[Zachary Whitley]

You sure you're not seeing anything in the logs? I gave it a try and it blew through heap space fairly quickly. (I allocated 8g to heap). What version of Stardog are you running. I tried it on 4.0.5

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[Evren Sirin]

We looked at the performance problems with this query and the problem
seems to be the query optimizer not handling {?token a ?class} pattern
efficiently. We created a ticket (#2835) for this issue.

For the patterns that retrieve types of an individual, Stardog will
execute additional queries behind the scenes. If these subqueries time
out a warning is printed in the log but the end user would receive
incomplete results and no warnings. This behavior is not ideal and
we'll make improvements here.

Best,
Evren

[Pavel Klinov]

Hello Steve,

We have improved performance of such queries and I can confirm that your query can be executed in about 2-3s (on my laptop). It yields the following results: owl:Thing, Token, StillImage, PreservedSpecimen and Specimen.

The changes will be included in the next release.

Best,

Pavel

--

[Steve Baskauf]

Pavel,
Thanks for letting me know.  I'm excited to try out the new release when it comes out.  Do you have any idea when it's going to be released?
Steve

Pavel Klinov wrote:

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-- 
Steven J. Baskauf, Ph.D., Senior Lecturer
Vanderbilt University Dept. of Biological Sciences

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[Michael Grove]

On Tue, Mar 8, 2016 at 10:34 AM, Steve Baskauf <steve....@vanderbilt.edu> wrote:

Pavel,
Thanks for letting me know.  I'm excited to try out the new release when it comes out.  Do you have any idea when it's going to be released?

The next version will be released in the next couple of weeks.

Cheers,

Mike