Hi Hugh.
Hi Timo,
Is the performance difference the same following repeat execution of the
prepared statement with URI binding ?
Yes.
it would still worth seeing some pseudo code showing how the prepared statement
is being set and the parameters passed to it ?
The PreparedStatement is created via
PreparedStatement stmt = connection.prepareStatement("sparql SELECT
DISTINCT ?dimension WHERE { ?item `iri(??)` `iri(??)` , `iri(??)` ,
?dimension }");
and the parameters are set via
stmt.setString(1, URI1);
stmt.setString(2, URI2);
stmt.setString(3, URI3);
I haven't got any special indexes configured.
Br,
Timo Westkämper
Best Regards
Hugh Williams
Professional Services
OpenLink Software
Web: http://www.openlinksw.com
Support: http://support.openlinksw.com
Forums: http://boards.openlinksw.com/support
Twitter: http://twitter.com/OpenLink
On 28 Mar 2011, at 15:09, Timo Westkämper wrote:
Hi.
The problem seems to be more general and not just related to predicates.
I have for example this query :
SELECT DISTINCT ?dimension WHERE { ?item ?_c3 ?_c4 , ?_c5 , ?dimension }
which I transform into the following query
sparql
SELECT DISTINCT ?dimension WHERE { ?item `iri(??)` `iri(??)` , `iri(??)` ,
?dimension }
with URI bindings for the three parameters.
The execution time for this approach is ~ 3s.
When I create the query instead like this :
SELECT DISTINCT ?dimension WHERE { ?item<URI1> <URI2> ,<URI3> , ?dimension }
I get an execution time of ~ 1s.
Does usage of prepared statements for SPARQL cause these issues or maybe
something else?
Br,
Timo Westkämper
On 03/28/2011 12:20 PM, Hugh Williams wrote:
Hi Timo,
Can you please provide more details on this issue possibly with some pseudo
code to demonstrate what is being done ? Are you getting the expected
performance benefits when using prepared statements to bind variables to
literal values but not when binding variables to predicates, for example ?
Best Regards
Hugh Williams
Professional Services
OpenLink Software
Web: http://www.openlinksw.com
Support: http://support.openlinksw.com
Forums: http://boards.openlinksw.com/support
Twitter: http://twitter.com/OpenLink
On 28 Mar 2011, at 08:40, Timo Westkämper wrote:
Hi.
I have noticed that when using SPARQL over JDBC as prepared statements I
get a huge performance penalty when binding variables acting as
predicates via prepared statements.
I'd like to bind all node constants via prepared statements. How can I
avoid the performance penalty?
Br,
Timo Westkämper
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