[dotNetRDF-Support] "Options.AlgebraOptimizations = false"

[George A. <geo...@gm...>]

Hello Support,

This is w.r.t my question on answers.semanticweb.com at "
http://answers.semanticweb.com/questions/21871/sparql-subsequent-query-on-retrieved-results-using-dotnetrdf
"

@Tomasz Pluskiewicz<http://answers.semanticweb.com/users/1788/tomasz-pluskiewicz>
:
suggested me to add
"
*Options.AlgebraOptimisation = false;*" before I make the queries; but my
doubt is should I addd them before both my queries or only before any one.

The problem code is as follows:

var graph = (IGraph)store.ExecuteQuery(@"
                    PREFIX sage: <
http://www.semanticsage.home.lc/LearningStyles.rdf#>
                    PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
                    PREFIX : <
http://www.semanticsage.home.lc/LearningStyles.rdf#>
                    CONSTRUCT
                    {
                       ?MTech :max ?maxScore
                    }
                    WHERE
                    {
                       SELECT ?MTech (MAX(?max) AS ?maxScore)
                       WHERE
                       {
                          SELECT ?MTech ?LessonType (SUM(?hasValue) AS ?max)
                          WHERE
                          {
                             ?MTech sage:attendsLessons ?Lesson.
                             ?Lesson sage:hasLessonType ?LessonType.
                             ?MTech sage:undergoesEvaluation ?Quiz.
                             ?Quiz sage:isForLesson ?Lesson.
                             ?MTech sage:hasQuizMarks ?QuizMarks.
                             ?QuizMarks sage:belongsToQuiz ?Quiz.
                             ?QuizMarks sage:hasValue ?hasValue.
                             ?Lesson sage:inRound '1'^^xsd:int.
                          }
                          GROUP BY ?MTech ?LessonType
                       }
                       GROUP BY ?MTech
                    }");

            // here a graph name is given to the result graph
            graph.BaseUri = new Uri("
http://semanticsage.home.lc/files/LearningStyles.rdf#maxValues");
            store.Add(graph, true);

            Object actualResults = store.ExecuteQuery(@"
                    PREFIX sage: <
http://www.semanticsage.home.lc/LearningStyles.rdf#>
                    PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
                    PREFIX : <
http://www.semanticsage.home.lc/LearningStyles.rdf#>
                    SELECT ?MTech ?LessonType ?max
                    WHERE
                    {
                       GRAPH <
http://semanticsage.home.lc/files/LearningStyles.rdf#maxValues>
                       {
                          ?MTech :max ?max
                       }
                       {
                            SELECT ?MTech ?LessonType (SUM(?hasValue) AS
?Score)
                            WHERE
                            {
                                ?MTech sage:attendsLessons ?Lesson.
                                ?Lesson sage:hasLessonType ?LessonType.
                                ?MTech sage:undergoesEvaluation ?Quiz.
                                ?Quiz sage:isForLesson ?Lesson.
                                ?MTech sage:hasQuizMarks ?QuizMarks.
                                ?QuizMarks sage:belongsToQuiz ?Quiz.
                                ?QuizMarks sage:hasValue ?hasValue.
                                ?Lesson sage:inRound '1'^^xsd:int.
                            }
                            GROUP BY ?MTech ?LessonType
                            ORDER BY ?MTech
                       }
                       FILTER(?Score = ?max)
                    }");

            DataTable table = new DataTable();
            DataRow row;

            if (actualResults is SparqlResultSet)
            {
                SparqlResultSet rset = (SparqlResultSet)actualResults;

                foreach (String var in rset.Variables)
                {
                    table.Columns.Add(new DataColumn(var));
                }

                MessageBox.Show(rset.Count().ToString());

                foreach (SparqlResult r in rset)
                {
                    row = table.NewRow();

                    foreach (String var in r.Variables)
                    {
                        if (r.HasValue(var) && r[var] != null)
                        {
                            INode n = r[var];
                            switch (n.NodeType)
                            {
                                case NodeType.Literal:
                                    //For literals you only want the
lexical value only so need to cast to
                                    //literal and access the Value property
                                    row[var] = ((ILiteralNode)n).Value;
                                    break;
                                case NodeType.Uri:
                                    Uri u = ((IUriNode)n).Uri;
                                    if (!u.Fragment.Equals(String.Empty))
                                    //u.Fragment is the fragment ID, the
#blah part of the URI
                                    {
                                        row[var] = u.Fragment.Substring(1);
                                    }
                                    else
                                    {
                                        row[var] = u.AbsoluteUri;
                                    }
                                    break;
                                default:
                                    //For any other node we just want the
string form so
                                    //ToString() is sufficient
                                    row[var] = n.ToString();
                                    break;
                            }
                        }
                    }
                    table.Rows.Add(row);
                }
            }
            DataSet ds = new DataSet();
            ds.Tables.Add(table);
            dataGridRound1LS.DataSource = ds.Tables[0];

The query is perfect but it returns no values on my system, whereas it is
working perfectly fine for@Tomasz
Pluskiewicz<http://answers.semanticweb.com/users/1788/tomasz-pluskiewicz>
.

Could someone provide me with a solution.

My RDF is available at: http://semanticsage.home.lc/files/LearningStyles.rdf

The project containing only the problematic code is available at:
http://semanticsage.home.lc/files/MaxValueCalculationCheck.rar

As of now the project contains dotNetRDF version 0.9 (the one available
from NuGet). I have even downloaded the latest nightly build and checked on
it, but still the same error.
-- 
Regards,*

George Abraham*
M.Tech CSE, VIT University
*m:* +91-8870456778 | *e:* geo...@gm...,
geo...@vi... <geo...@vi...>