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  1. Blazegraph (by SYSTAP)
  2. BLZG-8997

Ordered results in solution set - inconsistent results

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    Details

    • Type: Bug
    • Status: Open
    • Priority: Medium
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: Bigdata RDF Database
    • Labels:
      None

      Description

      Hi!
      On our Blazegraph instances (version 2.1.2) we investigated usage of features regarding
      ordered values in solution sets. It is use case described within,
      https://wiki.blazegraph.com/wiki/index.php/SPARQL_Update#Named_Solution_Sets
      which is used for paging through data set.
      We ran into problems with this. For sample data in attachment we made solution set with:

      {{prefix ex: <https://example.org/>
      prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
      prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
      prefix xml: <http://www.w3.org/XML/1998/namespace>
      prefix xsd: <http://www.w3.org/2001/XMLSchema#>

      INSERT INTO %entity_label
      SELECT ?e ?e_l
      WHERE {
      SELECT ?e ?e_l
      WHERE

      { ?e a ex:c . ?e rdfs:label ?e_l . }

      ORDER BY ?e
      }}}

      and when queried with :

      {{prefix ex: <https://example.org/>
      SELECT ?e ?e_l
      WHERE

      { INCLUDE %entity_label }

      LIMIT 3
      OFFSET 97}}

      we get proper results which are:

      {{<https://example.org/c/e/3eyl1r2> label 3eyl1r2
      <https://example.org/c/e/3f06245> label 3f06245
      <https://example.org/c/e/3funi1b> label 3funi1b}}

      but not always. We also get wrong data like

      {{<https://example.org/c/e/73fequm> label 73fequm
      <https://example.org/c/e/73wns10> label 73wns10
      <https://example.org/c/e/740peif> label 740peif
      }}
      or else, from time to time.

      Please, can you look at this problem? It breaks regular use case for above mentioned
      feature described in link.

      Best regards,
      Adam

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            Assignee:
            beebs Brad Bebee
            Reporter:
            kotlenik Adam Stanojevic
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              Dates

              Created:
              Updated: