ISSUE-41: Define how rr:column, rr:template, etc. handle NULL column values

NULL column handling

Define how rr:column, rr:template, etc. handle NULL column values

State:
CLOSED
Product:
R2RML
Raised by:
David McNeil
Opened on:
2011-05-11
Description:
As far as I can see the R2RML spec doesn't address how NULL column values are handled by the rr:column and rr:template properties (are there others affected by this?).

I think possible answers are:

1) throw an error
2) do not produce triples for these rows
3) something else?

Add wording to the spec to address this.
Related Actions Items:
No related actions
Related emails:
  1. update ACTION-136 [Fwd: ACTION-136] (from souripriya.das@oracle.com on 2011-07-12)
  2. Re: ISSUE-41 bNode semantics: Information preservation (from me@alexdeleon.name on 2011-05-24)
  3. Re: ISSUE-41 bNode semantics: Information preservation (from franconi@inf.unibz.it on 2011-05-24)
  4. Re: ISSUE-41 bNode semantics: Information preservation (from richard@cyganiak.de on 2011-05-24)
  5. Re: ISSUE-41 bNode semantics: Information preservation (from richard@cyganiak.de on 2011-05-24)
  6. ISSUE-41 bNode semantics: Information preservation (from marcelo.arenas1@gmail.com on 2011-05-23)
  7. Re: RDB2RDF WG agenda for 2011-05-24 meeting 1600 UTC (from michael.hausenblas@deri.org on 2011-05-22)
  8. Re: RDB2RDF WG agenda for 2011-05-24 meeting 1600 UTC (from bertails@w3.org on 2011-05-21)
  9. RDB2RDF WG agenda for 2011-05-24 meeting 1600 UTC (from michael.hausenblas@deri.org on 2011-05-21)
  10. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-20)
  11. Re: Q: ISSUE-41 bNode semantics (from richard@cyganiak.de on 2011-05-20)
  12. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-20)
  13. Fwd: Q: ISSUE-41 bNode semantics (from richard@cyganiak.de on 2011-05-20)
  14. Re: Q: ISSUE-41 bNode semantics (from juanfederico@gmail.com on 2011-05-19)
  15. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-19)
  16. Re: Dealing with RDB NULL values (was: Q: ISSUE-41 bNode semantics) (from franconi@inf.unibz.it on 2011-05-19)
  17. Re: Q: ISSUE-41 bNode semantics (from dmcneil@revelytix.com on 2011-05-19)
  18. Re: NULLs and the direct mapping (ISSUE-42) (was: Re: Q: ISSUE-41 bNode semantics) (from richard@cyganiak.de on 2011-05-19)
  19. Re: Q: ISSUE-41 bNode semantics (from richard@cyganiak.de on 2011-05-19)
  20. Re: Dealing with RDB NULL values (was: Q: ISSUE-41 bNode semantics) (from franconi@inf.unibz.it on 2011-05-19)
  21. Re: Dealing with RDB NULL values (was: Q: ISSUE-41 bNode semantics) (from juanfederico@gmail.com on 2011-05-19)
  22. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-19)
  23. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-19)
  24. Re: Dealing with RDB NULL values (was: Q: ISSUE-41 bNode semantics) (from franconi@inf.unibz.it on 2011-05-19)
  25. Re: Dealing with RDB NULL values (was: Q: ISSUE-41 bNode semantics) (from michael.hausenblas@deri.org on 2011-05-19)
  26. NULLs and the direct mapping (ISSUE-42) (was: Re: Q: ISSUE-41 bNode semantics) (from richard@cyganiak.de on 2011-05-19)
  27. Re: Dealing with RDB NULL values (was: Q: ISSUE-41 bNode semantics) (from juanfederico@gmail.com on 2011-05-19)
  28. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-19)
  29. Re: NULLs and the direct mapping (ISSUE-42) (was: Re: Q: ISSUE-41 bNode semantics) (from dmcneil@revelytix.com on 2011-05-19)
  30. Re: Dealing with RDB NULL values (was: Q: ISSUE-41 bNode semantics) (from franconi@inf.unibz.it on 2011-05-19)
  31. Re: Q: ISSUE-41 bNode semantics (from dmcneil@revelytix.com on 2011-05-19)
  32. Re: Q: ISSUE-41 bNode semantics (from bertails@w3.org on 2011-05-19)
  33. Re: Q: ISSUE-41 bNode semantics (from bertails@w3.org on 2011-05-19)
  34. Re: Q: ISSUE-41 bNode semantics (from dmcneil@revelytix.com on 2011-05-19)
  35. Re: Q: ISSUE-41 bNode semantics (from bertails@w3.org on 2011-05-19)
  36. Re: Dealing with RDB NULL values (was: Q: ISSUE-41 bNode semantics) (from dmcneil@revelytix.com on 2011-05-19)
  37. Re: Q: ISSUE-41 bNode semantics (from dmcneil@revelytix.com on 2011-05-19)
  38. Re: Q: ISSUE-41 bNode semantics (from bertails@w3.org on 2011-05-19)
  39. Re: Q: ISSUE-41 bNode semantics (from dmcneil@revelytix.com on 2011-05-19)
  40. Re: Q: ISSUE-41 bNode semantics (from richard@cyganiak.de on 2011-05-19)
  41. Dealing with RDB NULL values (was: Q: ISSUE-41 bNode semantics) (from michael.hausenblas@deri.org on 2011-05-19)
  42. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-19)
  43. Re: Q: ISSUE-41 bNode semantics (from richard@cyganiak.de on 2011-05-19)
  44. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-18)
  45. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-18)
  46. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-18)
  47. Re: Q: ISSUE-41 bNode semantics (from richard@cyganiak.de on 2011-05-18)
  48. Re: Q: ISSUE-41 bNode semantics (from bertails@w3.org on 2011-05-18)
  49. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-18)
  50. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-18)
  51. Re: Q: ISSUE-41 bNode semantics (from bertails@w3.org on 2011-05-18)
  52. Re: Q: ISSUE-41 bNode semantics (from bertails@w3.org on 2011-05-18)
  53. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-18)
  54. Re: Q: ISSUE-41 bNode semantics (from richard@cyganiak.de on 2011-05-18)
  55. Re: Q: ISSUE-41 bNode semantics (from phayes@ihmc.us on 2011-05-18)
  56. Re: Q: ISSUE-41 bNode semantics (from bertails@w3.org on 2011-05-18)
  57. Re: Q: ISSUE-41 bNode semantics (from bertails@w3.org on 2011-05-18)
  58. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-18)
  59. Re: Q: ISSUE-41 bNode semantics (from eric@w3.org on 2011-05-18)
  60. Re: Q: ISSUE-41 bNode semantics (from michael.hausenblas@deri.org on 2011-05-18)
  61. Re: Q: ISSUE-41 bNode semantics (from dmcneil@revelytix.com on 2011-05-18)
  62. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-18)
  63. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-18)
  64. Re: Q: ISSUE-41 bNode semantics (from juanfederico@gmail.com on 2011-05-18)
  65. Re: Q: ISSUE-41 bNode semantics (from michael.hausenblas@deri.org on 2011-05-18)
  66. Re: Q: ISSUE-41 bNode semantics (from bertails@w3.org on 2011-05-18)
  67. Re: ISSUE-41 What are the options? (from bertails@w3.org on 2011-05-18)
  68. Re: Q: ISSUE-41 bNode semantics (from dmcneil@revelytix.com on 2011-05-18)
  69. Re: Q: ISSUE-41 bNode semantics (from michael.hausenblas@deri.org on 2011-05-18)
  70. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-18)
  71. ISSUE-41 What are the options? (from ashok.malhotra@oracle.com on 2011-05-18)
  72. Re: Q: ISSUE-41 bNode semantics (from michael.hausenblas@deri.org on 2011-05-18)
  73. Re: Q: ISSUE-41 bNode semantics (from richard@cyganiak.de on 2011-05-18)
  74. Re: [ISSUE-41 and ISSUE-42] What do people think of NULLs (from michael.hausenblas@deri.org on 2011-05-18)
  75. Re: [ISSUE-41 and ISSUE-42] What do people think of NULLs (from franconi@inf.unibz.it on 2011-05-18)
  76. Re: Q: ISSUE-41 bNode semantics (from franconi@inf.unibz.it on 2011-05-18)
  77. Re: Q: ISSUE-41 bNode semantics (from ivan@w3.org on 2011-05-18)
  78. [ISSUE-41 and ISSUE-42] What do people think of NULLs (from juanfederico@gmail.com on 2011-05-17)
  79. Re: Information Preserving and ISSUE-41 (from juanfederico@gmail.com on 2011-05-17)
  80. Re: ISSUE-41 - NULL handling - Proposal (from dmcneil@revelytix.com on 2011-05-17)
  81. Re: Q: ISSUE-41 bNode semantics (from phayes@ihmc.us on 2011-05-17)
  82. Re: ISSUE-41 - NULL handling - Proposal (from richard@cyganiak.de on 2011-05-17)
  83. ISSUE-41 - NULL handling - Proposal (from dmcneil@revelytix.com on 2011-05-17)
  84. Re: Q: ISSUE-41 bNode semantics (from richard@cyganiak.de on 2011-05-17)
  85. Re: Information Preserving and ISSUE-41 (from richard@cyganiak.de on 2011-05-17)
  86. Re: Information Preserving (from michael.hausenblas@deri.org on 2011-05-17)
  87. Q: ISSUE-41 bNode semantics (from michael.hausenblas@deri.org on 2011-05-17)
  88. Re: ISSUE-41 (NULL column handling): Define how rr:column, rr:template, etc. handle NULL column values [R2RML] (from privera.salas@gmail.com on 2011-05-11)
  89. Re: ISSUE-41 (NULL column handling): Define how rr:column, rr:template, etc. handle NULL column values [R2RML] (from juanfederico@gmail.com on 2011-05-11)
  90. Re: ISSUE-41 (NULL column handling): Define how rr:column, rr:template, etc. handle NULL column values [R2RML] (from richard@cyganiak.de on 2011-05-11)
  91. Re: Proposal for ISSUE-32, curly braces in joinCondition (from dmcneil@revelytix.com on 2011-05-11)
  92. ISSUE-41 (NULL column handling): Define how rr:column, rr:template, etc. handle NULL column values [R2RML] (from sysbot+tracker@w3.org on 2011-05-11)

Related notes:

See also http://www.w3.org/2001/sw/rdb2rdf/wiki/RDBNullValues

Michael Hausenblas, 19 May 2011, 08:41:46

This was resolved here:
http://www.w3.org/2011/05/24-rdb2rdf-minutes.html

RESOLUTION: resolve ISSUE-41 per dmcneil's proposal
1) by default R2RML will suppress triples when the subject, predicate, or object columns are NULL (this applies to any of the columns used in template expressions as well as direct column references)
2) if the application needs other handling for NULL values then a SQLQuery can be defined in the mapping to convert NULL values to some other application specific value
3) If one or more of the columns used in a rr:graphTemplate are NULL, then corresponding triples will not be generated either.

I believe that the latest R2RML Editor's Draft accurately reflects this.

Richard Cyganiak, 4 Jul 2011, 18:25:52

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Ashok Malhotra <ashok.malhotra@oracle.com>, Michael Hausenblas <michael.hausenblas@deri.org>, Chairs, Eric Prud'hommeaux <eric@w3.org>, Ivan Herman <ivan@w3.org>, Staff Contacts
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