On 2009-11-13 09.57, Jacek Sokulski wrote:
Forwarding to the list
2009/11/13 Niclas Hedhman <[email protected] <mailto:[email protected]>>
On Fri, Nov 13, 2009 at 12:21 PM, Niclas Hedhman <[email protected]
<mailto:[email protected]>> wrote:
> I think I have found out why you are seeing what you are seeing
> The underlying OpenRDF/Sesame requires one to specify which kind of
> indices one wants, and if none is given then it will not index the
> content, hence a linear search occurs.
Well it doesn't seem to be this either, since the default behavior in
NativeStore/TripleStore in OpenRDF is a "spoc, posc" index pair, and
the latter of those is what I think should be used.
Rickard, do you have any clues?
I reproduced this last night, and I'm seeing the same thing. When I
queried for property where name ="Lead1" -> FAST lookup and when I query
for name="Lead9999" -> SLOW lookup, so it is definitely doing a linear
lookup. I tried adding all indices, but that didn't help.
My GUESS is that the way we create the queries is not optimal. Right now
the query creates a "v1 <property> v2" tuple and then "FILTER
v2='Lead9999'" (or something like that). It might be that Sesame can't
optimize that properly, and we should instead try to query for "v1
<property> 'Lead9999'" directly. But it's a guess.
/Rickard
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