DAWG Query Sketch Test Cases

Abstract. This document lists a selection of queries that have been used in the discussions of the RDF Data Access Working Group.

Version 0.3, 23-06-2004

1. Query Testcases

The queries are given in an abstract query syntax, listing triples with variables to be bound and qnames. These triples that match a subgraph of the RDF graph to be queried and are listed, followed by and constrinats that apply to the variables. Variables are prefixed by the ? character.

1.1 Variable v's constant comparisons

Discussed at the 1st face to face meeting.

Purpose

This query highlights the difference in execution-complexity between two superficially similar queries.

Query

In this query the number of possbile matches for the constraint section gorws with |?x| × |?y| whereas with a fixed operand (as in ?xAge < 18) the number of possible matches grows with |?x|.


      ?x :marriedTo ?y

      ?x :age ?xAge

      ?y :age ?yAge

      

      ?xAge < ?yAge

1.2 Disjunstion

From http://lists.w3.org/Archives/Public/public-rdf-dawg/2004AprJun/0630.html

Purpose

Demonstrates disjustion operation

Data

Query


      ?n p2 C || ?n p3 D

Triple results

1.3 Nested optional arcs

From http://lists.w3.org/Archives/Public/public-rdf-dawg/2004AprJun/0598.html

Purpose

Demonstrates possible results for nested optional subgraphs.

Data


      A p1 B # truncates on optional 1 term 1

      A p2 C

  
      A2 p1 B # truncates on optional term 2

      A2 p2 C

      A2 p3 D2

  
      D2 p4 E2

  
      A3 p1 B # eliminates second optional

      A3 p2 C

      A3 p3 D3

  
      D3 p4 E3

      D3 p5 F3

  
      A4 p1 B # has all arcs

      A4 p2 C

      A4 p3 D4

  
      D4 p4 E4

      D4 p5 F4

      D4 p6 F4

Query

(~ indicates optional subgraph)


      ?n p1 B

      ?n p2 C

      ~(?n ?p3 ?d

        ?d p4 ?e

        ?d p5 ?f

        ~(?d p6 ?g))

Results


      +----------+----------+----------+----------+----------+

      |         n|         d|         e|         f|         g|

      +----------+----------+----------+----------+----------+

      |         A|      NULL|      NULL|      NULL|      NULL|

      |        A2|      NULL|      NULL|      NULL|      NULL|

      |        A3|        D3|        E3|        F3|      NULL|

      |        A4|        D4|        E4|        F4|        F4|

      +----------+----------+----------+----------+----------+

1.4 Optional triples

Purpose

Demonstrates possible bindings for queries containing optional components. From http://lists.w3.org/Archives/Public/public-rdf-dawg/2004AprJun/0652.html

Data


      :x :p :a
      :x :q :b

Query A

[] indicates optional triples


      [(:x :p ?v)]
      [(:x :q ?v)]

Results A


      +--------+
      |      v |
      +--------+
      |     :a |   matches the first part but then the second can't match
      |     :b |   matches the second part but not the first
      +--------+

Query B


      [(:x :p ?v)
       (:x :q ?v)]

Results B

has no match

1.5 Optional triples


       (?person foaf:name ?name)
      [(?person foaf:mbox ?mbox)]

Results

http://jena.hpl.hp.com/~afs/DAWG/Tests/dawg-result-001.n3


      +-------------------------------+
      | name    | mbox                |
      +-------------------------------+
      | "Bob"   | <mailto:bob@work>   |
      | "Bob"   | <mailto:bob@home>   |
      | "Eve"   | null                |
      | "Alice" | <mailto:alice@work> |
      +---------+---------------------+

1.6 Optional triples

Purpose

Demonstrates multi-triple graph pattern in optional part. This leads to a need for nested optionals: get the name or mbox of any people known by people in the FOAF datafile. From http://lists.w3.org/Archives/Public/public-rdf-dawg/2004JulSep/0044.html.

Data

http://jena.hpl.hp.com/~afs/DAWG/Tests/dawg-data-01.n3

Query

http://jena.hpl.hp.com/~afs/DAWG/Tests/dawg-query-002 (BRQL syntax)


       (?person foaf:name   ?name)
      [(?person foaf:knowns ?p2)
       (?p2     foaf:name   ?name2)]

Results

http://jena.hpl.hp.com/~afs/DAWG/Tests/dawg-result-002.n3


      +---------+-----------+
      | name    | name2     |
      +---------+-----------+
      | "Bob"   | "Alice"   |
      | "Alice" | "Bob"     |
      | "Eve"   | null      |
      +---------+-----------+

1.7 Optional triples

Purpose

Demonstrates multiple, independent optional clauses. From http://lists.w3.org/Archives/Public/public-rdf-dawg/2004JulSep/0044.html.

Data

http://jena.hpl.hp.com/~afs/DAWG/Tests/dawg-data-01.n3

Query

http://jena.hpl.hp.com/~afs/DAWG/Tests/dawg-query-003 (BRQL syntax)


       (?person rdf:type  foaf:Person)
      [(?person foaf:name ?name)]
      [(?person foaf:mbox ?mbox)]

Results

http://jena.hpl.hp.com/~afs/DAWG/Tests/dawg-result-003.n3


      +-----------+---------------------+
      | name      | mbox                |
      +-----------+---------------------+
      | "Bob"     | <mailto:bob@home>   |
      | "Bob"     | <mailto:bob@work>   |
      | null      | <fred@edu>          |
      | "Eve"     | null                |
      | "Alice"   | <mailto:alice@work> |
      +-----------+---------------------+