Thank you very much Jerven for your advice.
I will try it and let you know if the query is faster.
Kind regards,
Pantelis Natsiavas
2016-04-21 10:14 GMT+03:00 Jerven Tjalling Bolleman <
jerven.bolleman@sib.swiss>:
>
> As another virtuoso user.
> Can't you make a simpler query without a subselect?
>
> SELECT ?a
> FROM NAMED <b
> FROM NAMED <i>
> {
> GRAPH <b>
> {
> ?c d ?e .
> BIND(REPLACE(STR(?e), "f", "", "i") AS ?g)
> BIND(REPLACE(STR(?c), "f", "", "i") AS ?a)
> FILTER (?g = STR(?h)) .
> }
> GRAPH <i>
> {
> ?j <k> ?h .
> ?j <l> ?m .
> FILTER (REGEX(STR(?m), "n", "i"))*
> }
> }
>
> Mostly what is happening is that the STR casting makes it hard to
> optimize the joins as the input could have been anything not just IRIs.
>
> So the following might make things better if ?g and ?h are both supposed
> to be IRI's.
>
> SELECT ?a
> FROM NAMED <b
> FROM NAMED <i>
> {
> GRAPH <b>
> {
> ?c d ?e .
> BIND(IRI(REPLACE(STR(?e), "f", "", "i") AS ?g))
> BIND(REPLACE(STR(?c), "f", "", "i") AS ?a)
> }
> GRAPH <i>
> {
> ?j <k> ?g .
> ?j <l> ?m .
> FILTER (REGEX(STR(?m), "n", "i"))*
> }
> }
>
>
>
> On 21/04/16 08:42, Pantelis Natsiavas wrote:
> > Hello everybody.
> >
> > I built a SPARQL query using a nested subquery and noticed a huge
> > performance penalty. A simplified version of the query follows. Please
> > note that in the simplified query presented here I have only replaced
> > URIs in order to be more readable and left all the comparisons and
> > conversions in place as they could matter to the overall query
> performance.
> >
> > SELECT ?a
> > FROM NAMED <b>
> > {
> > GRAPH <b>
> > {
> > ?c d ?e .
> > BIND(REPLACE(STR(?e), "f", "", "i") AS ?g)
> > BIND(REPLACE(STR(?c), "f", "", "i") AS ?a)
> > FILTER (?g = STR(?h)) .
> > {
> > *SELECT ?h*
> > * FROM NAMED <i>*
> > * WHERE{*
> > * GRAPH <i>*
> > * {*
> > * ?j <k> ?h .*
> > * ?j <l> ?m .*
> > * FILTER (REGEX(STR(?m), "n", "i"))*
> > * }*
> > * }*
> > }
> > }
> > }
> >
> > If I execute the above query as a nested query I get a response after 40
> > seconds. If I execute the nested query first (shown using bold
> > characters) and put the result in the filter of the outer query, I get
> > the result in a matter of 3 seconds (total). Given the simplicity of my
> > rationale, I would expect a similar logic and performance from virtuoso.
> >
> > Have you noticed such a performance penalty before? Am I missing
> > something? Is there a more efficient way to build the above query? Could
> > the above query's performance penalty be caused due to a combination of
> > the usage of BIND, REPLACE, STR and nested queries in different graphs?
> >
> > Please note that I am using Virtuoso Version: 07.20.3214, Build: Oct 14
> > 2015 (I built it from source files).
> >
> > Kind regards,
> > Pantelis Natsiavas
> >
> >
> >
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>
> --
> -------------------------------------------------------------------
> Jerven Bolleman Jerven.Bolleman@sib.swiss
> SIB Swiss Institute of Bioinformatics Tel: +41 (0)22 379 58 85
> CMU, rue Michel Servet 1 Fax: +41 (0)22 379 58 58
> 1211 Geneve 4,
> Switzerland www.sib.swiss - www.uniprot.org
> Follow us at https://twitter.com/#!/uniprot
> -------------------------------------------------------------------
>
>
> ------------------------------------------------------------------------------
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> Manager
> Applications Manager provides deep performance insights into multiple
> tiers of
> your business applications. It resolves application problems quickly and
> reduces your MTTR. Get your free trial!
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