Re: [Bigdata-developers] Query projections and multiple VALUES clauses

[Bryan T. <br...@sy...>]

Brad, can you publish that branch on Sourceforge git so people can play with it?

Thanks,
Bryan
----
Bryan Thompson
Chief Scientist & Founder
SYSTAP, LLC
4501 Tower Road
Greensboro, NC 27410
br...@sy...
http://blazegraph.com
http://blog.bigdata.com
http://mapgraph.io

Blazegraph™ is our ultra high-performance graph database that supports
both RDF/SPARQL and Tinkerpop/Blueprints APIs.  MapGraph™ is our
disruptive new technology to use GPUs to accelerate data-parallel
graph analytics.

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On Fri, May 15, 2015 at 1:20 PM, Michael Schmidt <ms...@me...> wrote:
> Dear Lee,
>
> thanks for reporting the two issues!
>
> We have identified the problems causing the behavior (see my comment in the
> parent task http://jira.blazegraph.com/browse/BLZG-1141). A correctness fix
> for both issues is available in branch BLZG48and50, however the fix might
> induce some performance regressions. We want to look at performance in more
> depth before merging into master (probably as part of a more exhaustive
> refactoring), so it might take a while until this will appear in master.
>
> Best,
> Michael
>
>
> On 13 May 2015, at 16:06, Bryan Thompson <br...@sy...> wrote:
>
> Lee,
>
> Many thanks. I will assign them to Michael (Cc) to take an initial look.
>
> Thanks,
> Bryan
> ----
> Bryan Thompson
> Chief Scientist & Founder
> SYSTAP, LLC
> 4501 Tower Road
> Greensboro, NC 27410
> br...@sy...
> http://blazegraph.com
> http://blog.bigdata.com
> http://mapgraph.io
>
> Blazegraph™ is our ultra high-performance graph database that supports
> both RDF/SPARQL and Tinkerpop/Blueprints APIs.  MapGraph™ is our
> disruptive new technology to use GPUs to accelerate data-parallel
> graph analytics.
>
> CONFIDENTIALITY NOTICE:  This email and its contents and attachments
> are for the sole use of the intended recipient(s) and are confidential
> or proprietary to SYSTAP. Any unauthorized review, use, disclosure,
> dissemination or copying of this email or its contents or attachments
> is prohibited. If you have received this communication in error,
> please notify the sender by reply email and permanently delete all
> copies of the email and its contents and attachments.
>
>
> On Wed, May 13, 2015 at 10:03 AM, Lee Kitching <le...@sw...> wrote:
>
> Hi Bryan,
>
> I've raised these at http://jira.blazegraph.com/browse/BLZG-48 and
> http://jira.blazegraph.com/browse/BLZG-50.
>
> Thanks
>
> On Wed, May 13, 2015 at 12:41 PM, Bryan Thompson <br...@sy...> wrote:
>
>
> Lee,
>
> These definitely look like bugs.  Can you please file tickets at
> http://jira.blazegraph.com and include sample data and expected
> solutions for each?  We will try to get the fixes into the 1.5.2
> release.
>
> Thanks,
> Bryan
> ----
> Bryan Thompson
> Chief Scientist & Founder
> SYSTAP, LLC
> 4501 Tower Road
> Greensboro, NC 27410
> br...@sy...
> http://blazegraph.com
> http://blog.bigdata.com
> http://mapgraph.io
>
> Blazegraph™ is our ultra high-performance graph database that supports
> both RDF/SPARQL and Tinkerpop/Blueprints APIs.  MapGraph™ is our
> disruptive new technology to use GPUs to accelerate data-parallel
> graph analytics.
>
> CONFIDENTIALITY NOTICE:  This email and its contents and attachments
> are for the sole use of the intended recipient(s) and are confidential
> or proprietary to SYSTAP. Any unauthorized review, use, disclosure,
> dissemination or copying of this email or its contents or attachments
> is prohibited. If you have received this communication in error,
> please notify the sender by reply email and permanently delete all
> copies of the email and its contents and attachments.
>
>
> On Wed, May 13, 2015 at 6:51 AM, Lee Kitching <le...@sw...> wrote:
>
> Hi,
>
> We are trying to migrate our native Sesame database to Blazegraph,
> however
> we are encountering a problem with the following query which returns no
> results in Blazegraph:
>
> SELECT DISTINCT ?uri WHERE {
>  {
>    SELECT DISTINCT (?uri_d as ?uri) WHERE {
>      VALUES ?type { <http://type1> <http://type2> <http://type3> }
>      VALUES ?dg { <http://graph1> }
>      GRAPH ?dg { ?uri_d a ?type . }
>    }
>  }
>  MINUS
>  {
>    SELECT DISTINCT (?uri_l as ?uri) WHERE {
>    VALUES ?type { <http://type1> <http://type2> <http://type3> }
>    VALUES ?lg { <http://graph2> }
>    GRAPH ?lg { ?uri_l a ?type . }
>    }
>  }
> }
>
> This returns a single result in Sesame since the first subquery returns
> one
> result and the subquery in the MINUS clause returns none. Executing the
> first subquery
>
> SELECT DISTINCT (?uri_d as ?uri) WHERE {
>  VALUES ?type { <http://type1> <http://type2> <http://type3> }
>  VALUES ?dg { <http://graph1> }
>  GRAPH ?dg { ?uri_d a ?type . }
> }
>
> returns 0 results in Blazegraph, however moving the single graph value
> into
> the GRAPH clause:
>
> SELECT DISTINCT (?uri_d as ?uri) WHERE {
>  VALUES ?type { <http://type1> <http://type2> <http://type3> }
>  GRAPH <http://graph1> { ?uri_d a ?type . }
> }
>
> returns the expected result. Combining the two VALUES clauses into one:
>
> SELECT DISTINCT (?uri_d as ?uri) WHERE {
>  VALUES (?type ?dg) { (<http://type1> <http://graph1>) (<http://type2>
> <http://graph1>) (<http://type3> <http://graph1>) }
>  GRAPH ?dg { ?uri_d a ?type . }
> }
>
> also returns the result. Does Blazegraph support multiple VALUES clauses
> in
> the same query? I would expect the three queries above to be equivalent
> (in
> the case of a single graph).
>
> Another issue is that Blazegraph appears to be inconsistent when
> projecting
> variables from inner subqueries. The query:
>
> SELECT DISTINCT (?uri_d as ?uri) WHERE {
>  VALUES ?type { <http://type1> <http://type2> <http://type3> }
>  GRAPH <http://graph1> { ?uri_d a ?type . }
> }
>
> returns the expected result, however wrapping this in another
> projection:
>
> SELECT ?uri WHERE {
>  SELECT (?uri_d as ?uri) WHERE {
>    VALUES ?type { <http://type1> <http://type2> <http://type3> }
>    GRAPH <http://graph1> { ?uri_d a ?type . }
>  }
> }
>
> causes no results to be returned. Surprisingly, projecting an unused
> variable from the inner query:
>
> SELECT ?uri WHERE {
>  SELECT ?type (?uri_d as ?uri) WHERE {
>    VALUES ?type { <http://type1> <http://type2> <http://type3> }
>    GRAPH <http://graph1> { ?uri_d a ?type . }
>  }
> }
>
> causes the result to be returned again.
>
> These two issues appear to be preventing the original MINUS query from
> returning the expected results. Could you confirm these behaviours are
> bugs?
> I tried looking on the issue tracker but couldn't find anything directly
> related.
>
> Thanks
>
>
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