DISTINCT and ORDER BY bug

[Yves Raimond]

Hello!

We just noticed the following weird behavior, when combining DISTINCT with ORDER BY.

Load the following Turtle document in 4store:

  @prefix : <http://example.com/> .
  :thing1 :property1 [ :weight 0.7 ; :property2 :thing2 ] .
  :thing1 :property1 [ :weight 0.8 ; :property2 :thing2 ] .
  :thing2 :property3 :thing3 .
  :thing2 :property3 :thing4 .

Execute the following SPARQL query:

select distinct ?d where {?b <http://example.com/weight> ?weight . ?b <http://example.com/property2> ?c . ?c <http://example.com/property3> ?d} order by desc(?weight)

Expected results (one row per distinct bindings for ?d, and the order is actually undefined, as both bindings have the same ordering):
- http://example.com/thing4
- http://example.com/thing3

Actual results:
- http://example.com/thing4
- http://example.com/thing3
- http://example.com/thing4
- http://example.com/thing3

Cheers,
Yves

[Steve Harris]

Interesting - thanks for the bug report Yves, I've recreated it with Git HEAD and I'll create a ticket for it.

- Steve

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