Here's the parse, hope it helps:
WHERE
{ VALUES ?sct_code { "298314008" }
?c skosxl:prefLabel _:b0 .
_:b0 lsu:code ?sct_code .
?c skos:inScheme lsu:SNOMEDCT_US
}
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
(prefix ((owl: <http://www.w3.org/2002/07/owl#>)
(rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>)
(skosxl: <http://www.w3.org/2008/05/skos-xl#>)
(skos: <http://www.w3.org/2004/02/skos/core#>)
(dcterms: <http://purl.org/dc/terms/>)
(rdfs: <http://www.w3.org/2000/01/rdf-schema#>)
(lsr: <https://resource.lingsoft.fi/>)
(id: <http://snomed.info/id/>)
(dcat: <http://www.w3.org/ns/dcat#>)
(dc: <http://purl.org/dc/elements/1.1/>)
(lsu: <https://www.lingsoft.fi/ns/umls/>))
(sequence
(table (vars ?sct_code)
(row [?sct_code "298314008"])
)
(bgp
(triple ?c skos:inScheme lsu:SNOMEDCT_US)
(triple ?c skosxl:prefLabel ??0)
(triple ??0 lsu:code ?sct_code)
)))
On 02/11/2022 12.32, rve...@dotnetrdf.org wrote:
For these kind of performance issues it is useful to see the SPARQL algebra for
the whole query, not just fragments of the query. You can use the qparse
command for the version of Jena you are using to see how it is optimising your
queries e.g.
qparse --explain --query example.rq
As Lorenz suggests this may be the optimiser making a bad guess at the
appropriate order in which to evaluate the triple patterns within the BGP but
without the larger query context or the algebra all we can do is guess.
Rob
From: Mikael Pesonen <mikael.peso...@lingsoft.fi>
Date: Tuesday, 1 November 2022 at 12:53
To: users@jena.apache.org <users@jena.apache.org>
Subject: Re: Weird sparql problem
Diferent case, but again hanging makes no sense to user, whatever are
the technical reasons.
VALUES ?sct_code { "298314008" }
?c skosxl:prefLabel [ lsu:code ?sct_code ]
returns one row immediately, but
VALUES ?sct_code { "298314008" }
?c skosxl:prefLabel [ lsu:code ?sct_code ]; skos:inScheme
lsu:SNOMEDCT_US
hangs forever
skos:inScheme lsu:SNOMEDCT_US;
On 18/10/2022 9.08, Lorenz Buehmann wrote:
Hi,
comments inline
On 17.10.22 14:35, Mikael Pesonen wrote:
This works as a separate query, but not in a the middle, since ?s
gets new values instead of binding to previous ?s.
{ select ?t where {
?s a ?t .
} limit 10}
?t skos:prefLabel ?l
In the middle of what? Subqueries will be evaluated first - if you
really want labels for classes, you should use a DISTINCT in the
subquery such that the intermediate result is small, there shouldn't
be that many classes, but many instances with the same class, thus,
the join would be more expensive than necessary.
On 17/10/2022 14.56, Mikael Pesonen wrote:
?s a ?t .
?t skos:prefLabel ?l
returns 3 million triples. Maybe it's related to this?
I don't see how this should be related to your initial query where ?s
was bound, which in my opinion should be an easy join. Is it possible
for you to share the dataset somehow? Also, what you can do is to
compute statistics for the TDB database with tdbstats tool [1] from
commandline and put it into the TDB folder. But even without the query
plan should take the first triple pattern, use the spo index as s and
p are bound, then pass the bindings of ?o to the evaluation of the
second triple pattern
[1]
https://jena.apache.org/documentation/tdb/optimizer.html#generating-a-statistics-file
On 21/09/2022 9.15, Lorenz Buehmann wrote:
Weird, only 10M triples and each triple pattern returns only 1
binding, thus, the size is tiny - honestly I can't think of
anything except for open connections, but as you mentioned, running
the queries with only one triple pattern works as expected, so that
too many open connections shouldn't be an issue most likely.
Can you reproduce this behavior with newer Jena versions like 4.6.1?
Or can you reproduce this on different servers as well?
Is it also stuck of your run the query directly after you restart
Fuseki?
On 19.09.22 13:49, Mikael Pesonen wrote:
On 15/09/2022 17.48, Lorenz Buehmann wrote:
Forgot:
- size of result for each triple pattern? Might affect if hash
join can be used.
It's one row for each.
- your hardware?
Normal server with 16gigs mem.
- is it just the first query after starting Fuseki? Connections
have been closed? Note, there was also a bug in a recent Jena
version, but only with TDB and too many open connections. It has
been resolved with release 4.6.1.
Jena has been running quite a while.
Might not be related, but I'm mentioning all things here
nevertheless.
On 15.09.22 11:16, Mikael Pesonen wrote:
This returns one row fast, say :C1
SELECT *
FROM <https://a.b.c>
WHERE {
<https://x.y.z> a ?t .
#?t skos:prefLabel ?l
}
and this too:
SELECT *
FROM <https://a.b.c>
WHERE {
#<https://x.y.z> a ?t .
:C1 skos:prefLabel ?l
}
But this always hangs until timeout
SELECT *
FROM <https://a.b.c>
WHERE {
<https://x.y.z> a ?t .
?t skos:prefLabel ?l
}
What am I missing here? I'm using Fuseki web GUI. Thanks!
--
Lingsoft - 30 years of Leading Language Management
www.lingsoft.fi<http://www.lingsoft.fi>
Speech Applications - Language Management - Translation - Reader's and Writer's
Tools - Text Tools - E-books and M-books
Mikael Pesonen
System Engineer
e-mail: mikael.peso...@lingsoft.fi
Tel. +358 2 279 3300
Time zone: GMT+2
Helsinki Office
Eteläranta 10
FI-00130 Helsinki
FINLAND
Turku Office
Kauppiaskatu 5 A
FI-20100 Turku
FINLAND
--
Lingsoft - 30 years of Leading Language Management
www.lingsoft.fi
Speech Applications - Language Management - Translation - Reader's and Writer's
Tools - Text Tools - E-books and M-books
Mikael Pesonen
System Engineer
e-mail: mikael.peso...@lingsoft.fi
Tel. +358 2 279 3300
Time zone: GMT+2
Helsinki Office
Eteläranta 10
FI-00130 Helsinki
FINLAND
Turku Office
Kauppiaskatu 5 A
FI-20100 Turku
FINLAND
