Hi,
Thanks for your interest.
I know that hasNext() executes the query. When I debug, I see that only one
http request is sent to the sparql endpoint. Then, I think the first result
should take long time if there is only one http request. However, it takes
long time to get all results, but not the first one.
Best,
Burak
2013/2/28 Andy Seaborne <a...@apache.org>
> On 28/02/13 09:13, Burak Yönyül wrote:
>
>> Hi,
>>
>> I am having a problem about ARQ's parse time of a big result set. (ARQ
>> version 2.9.4)
>>
>> I execute two queries which produce similar result sets. I attached them.
>>
>
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>
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>
> Answer below:
>
>
> The first one contains a filter block ("one_of_filter" type) and returns
>> around 9000 results. On the other hand, the second one doesn't have a
>> filter block and has a limit element to produce same number of results
>> with the former query. (Not the same results, but only the same result
>> count)
>>
>> The problem is that it takes 60 seconds to parse the result of the first
>> query while it only takes 0.4 seconds to parse the result of the second
>> query. I'm executing these queries on a sparql endpoint of drugbank
>> dataset which is loaded on a local 4Store server. ( Here's the link to
>> download considered drugbank dataset:
>> https://docs.google.com/file/**d/0B3zcaLjQc0_**yaEdsTUdxQ1ZJc28/edit?usp=
>> **sharing<https://docs.google.com/file/d/0B3zcaLjQc0_yaEdsTUdxQ1ZJc28/edit?usp=sharing>
>> )
>>
>> I execute the query with the code given below:
>>
>> QueryExecution queryExecution =
>> QueryExecutionFactory.**sparqlService("http://**localhost:8000/sparql/<http://localhost:8000/sparql/>",
>> query);
>> ResultSet resultSet = queryExecution.execSelect();
>> while (resultSet.hasNext()) { resultSet.next(); ... }
>>
>> Reading the first result of two queries take similar times. But reading
>> the all result set of the first query takes a long time. Do you have any
>> idea why parsing two queries are different?
>>
>
> They don't take the same time - queryExecution.execSelect does not
> complete the query - it sets it up.
>
> ARQ is streaming and does nto take a copy of the results on execSelect.
> It reads the results are pulled in hasNext. The server is taking 60s for
> the more expensive query presumably because it needs to scan a lot more
> results to filter out the down to 9000. There are optimizations that you
> can do on ?x IN (...) (if that is what a one_of_filter is) but I don't know
> if 4Store does them, or can given it's architecture.
>
> Try this:
>
> ResultSet resultSet = queryExecution.execSelect();
> resultSet = ResultSetFactory.copyResult(**resultSet) ;
>
> to consume the data immediately before starting the loop.
>
> Andy
>
>
>
>
>> Best Regards,
>> Burak Yönyül
>>
>
>
