Hi Andy,
Apologize for my lacking knowledge on Jena codebase, I am still learning at
slow pace.
I guess the stuff in OpExecutor is the algebra that you referred to, right? If
yes, then the answer is I have implemented some of them.
I looked at Jena's code, and found AggCount class, is that the one I should
subclass? And where would be the integration point with my code?
Right now for this query, "SELECT (COUNT(*) AS ?no) { ?s ?p ?o }", my code will
bind all those variables :-(
I guess my code needs to behave same like TDB, so when it sees COUNT(*), it
won't bind those variables, and instead just counting number of rows.
If there is existing sample code in Jena's repo, which does exactly what I am
looking for, then that'd be helpful too.
Thanks,
Z
________________________________________
From: Andy Seaborne <[email protected]>
Sent: Monday, November 9, 2015 2:50 PM
To: [email protected]
Subject: Re: total triples
On 09/11/15 18:58, Zen 98052 wrote:
> Thanks Martynas!
> Shouldn't it call graph's size(), which in turn calls graphBaseSize()?
Depends what "it" is. Have you implemented some or all of the algebra
or are you using the general query engine over a graph/dataset?
ARQ's general query engine does not call Graph.size.
COUNT(*) is a general operator and COUNT(*) means count rows.
So it counts the rows of the pattern:
other queries work:
SELECT (COUNT(*) AS ?no) {
{ <someuri> ?p ?o } UNION { GRAPH ?g { <someuri> ?p ?o } } }
(TDB uses delayed evaluation of results so it never pulls the real nodes
for variables in COUNT(*)).
Andy
> My graph implementation overrides graphBaseSize(), but looks like it never
> got called for that query.
>
> Thanks,
> Z
> ________________________________________
> From: Martynas Jusevičius <[email protected]>
> Sent: Monday, November 9, 2015 9:52 AM
> To: [email protected]
> Subject: Re: total triples
>
> That would only count triples in the default graph and omit triples in
> named graphs. To account for them, you would need something like
>
> SELECT (COUNT(*) AS ?no) { { ?s ?p ?o } UNION { GRAPH ?g { ?s ?p ?o } } }
>
> On Mon, Nov 9, 2015 at 3:47 PM, Zen 98052 <[email protected]> wrote:
>> What is the most efficient way to get total number of triples?
>>
>> Is this query below the only way?
>>
>> SELECT (COUNT(*) AS ?no) { ?s ?p ?o }
>>
>>
>> Thanks,
>>
>> Z
