[Virtuoso-users] Query comparison

[Sebastian Trüg]

Hi list,

again I have a question about query performance: why is there a big
difference in query execution time between

select distinct ?r ?v where {
  { ?r ?v1 ?v2 .
    FILTER(bif:contains(?v2, "'hello' AND 'world'")) .
  }
  UNION
  { ?r ?v1 ?v3 .
    ?v3 ?v4 ?v2 .
    ?v4 rdfs:subPropertyOf rdfs:label .
    FILTER(bif:contains(?v2, \"'hello' AND 'world'\")) .
  } .
  ?r nao:userVisible ?v
}

and

select distinct ?r where {
  { ?r ?v1 ?v2 .
    FILTER(bif:contains(?v2, \"'hello' AND 'world'\")) .
  }
  UNION
  { ?r ?v1 ?v3 .
    ?v3 ?v4 ?v2 .
    ?v4 rdfs:subPropertyOf rdfs:label .
    FILTER(bif:contains(?v2, \"'hello' AND 'world'\")) .
  } .
  ?r nao:userVisible 1
}

The first one returns in no time while the second one takes time.

Any ideas?

Cheers,
Sebastian