How do you set up the model you're querying?
Richard
On 2 Apr 2013, at 12:44, Anastasiya Goncharova <slmn...@gmail.com> wrote:
> I think, I need to provide query that I run.
>
> SPARQl query is:
>
> PREFIX vocab: <http://www.vocab.de/vocab/> SELECT ?x ?y ?z { ?id
> vocab:port39390_facts_relation ?z. ?id vocab:port39390_facts_arg1 ?x. ?id
> vocab:port39390_facts_arg2 ?y. FILTER (?z = 'isLeaderOf')}
>
> D2RQ rewrites this query into 2 SQL (as it is written to console):
>
> 11:46:01 INFO SQLIterator :: SELECT DISTINCT
> "T2_port39390_facts"."arg2", "T1_port39390_facts"."id",
> "T3_port39390_facts"."arg1" FROM "port39390"."facts" AS "T1_port39390_facts",
> "port39390"."facts" AS "T2_port39390_facts", "port39390"."facts" AS
> "T3_port39390_facts" WHERE ("T1_port39390_facts"."id" =
> "T2_port39390_facts"."id" AND "T1_port39390_facts"."relation" = 'isLeaderOf'
> AND "T1_port39390_facts"."relation" IS NOT NULL AND
> "T2_port39390_facts"."arg2" IS NOT NULL AND "T2_port39390_facts"."id" =
> "T3_port39390_facts"."id" AND "T3_port39390_facts"."arg1" IS NOT NULL)
>
> 11:46:01 INFO SQLIterator :: SELECT DISTINCT
> "T1_port39390_facts"."id", "T4_port39390_facts"."arg2",
> "T2_port39390_facts"."relation", "T3_port39390_facts"."arg1" FROM
> "port39390"."facts" AS "T1_port39390_facts", "port39390"."facts" AS
> "T4_port39390_facts", "port39390"."facts" AS "T2_port39390_facts",
> "port39390"."facts" AS "T3_port39390_facts" WHERE ("T1_port39390_facts"."id"
> = "T4_port39390_facts"."id" AND "T2_port39390_facts"."id" =
> "T4_port39390_facts"."id" AND "T2_port39390_facts"."relation" IS NOT NULL AND
> "T3_port39390_facts"."arg1" IS NOT NULL AND "T3_port39390_facts"."id" =
> "T4_port39390_facts"."id" AND "T4_port39390_facts"."arg2" IS NOT NULL)
>
> So, second query considers 4 copies of the table and for 3 copies does a full
> scan on one of their columns (arg1, arg2, relation) and for 4th copy a full
> scan on all columns. Is it possible to prevent such behaviour and what the
> difference between query evaluation from Jena and in command line using
> d2r-query?
>
>
>
> 2013/4/2 Anastasiya Goncharova <slmn...@gmail.com>
>> Hello everyone,
>>
>> I have a large dataset that contains about 650 millions rows. I try to
>> evaluate query that returns about 8000 rows. When I run this query from
>> command line using d2r-query function, the result is returned fast enough.
>> But when I evaluate the same query from Jena using
>>
>> ResultSet rs = QueryExecutionFactory.create(query, RDFModel).execSelect();
>>
>> it takes too long. I was waiting for several hours and then have terminated
>> application without waiting the end of evaluation. Why does it happen and
>> how to improve a runtime?
>>
>> Best,
>>
>> Anastasiya
>
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