Dear Hugh,
I hope you are doing great.
We had the chance to exchange last year during the benchmark of Virtuoso for
Publications Office.
I joined ERA in September, and we are using Virtuoso as backend for a railway
infrastructure in Europe [1].
We have some problematic issues/queries for the application consuming RDF data
stored in Virtuoo
1- Wrong results for BIND depending on OPTIONAL/BIND order
We have the following query, where 2 different parameters are requested and we
want to also check if they are NYA or NA, for both.
# SPARQL query generated by ERA Search App
SELECT DISTINCT
?e2e8d0ff44169432a9b6a49d415768b6aeb230e6e308eacd14c58203edec7c1e
?5611b111a3e8b6a75f9cf140ebfc88a2400da808384163a68f6ea2b27feae0a2
?7c9eedbe297dee33d5692bb017576d5f90128c5a57245968861342c5d938bc15
?068c016b70a3e345e79f2c917aa68e82e0a103ed4a2d3a377fc7e6d65298e659
FROM http://data.europa.eu/949/graph/rinf
WHERE {
?e2e8d0ff44169432a9b6a49d415768b6aeb230e6e308eacd14c58203edec7c1e a
http://data.europa.eu/949/OperationalPoint.
?e2e8d0ff44169432a9b6a49d415768b6aeb230e6e308eacd14c58203edec7c1e
http://data.europa.eu/949/uopid
?bed82d131276294cde9b33e06fc5540daf5ce0a0ca03c6428b296bff9ff8e95b.
FILTER(lcase(str(?bed82d131276294cde9b33e06fc5540daf5ce0a0ca03c6428b296bff9ff8e95b))
= lcase("DEYBBMO"))
?e2e8d0ff44169432a9b6a49d415768b6aeb230e6e308eacd14c58203edec7c1e
http://data.europa.eu/949/track
?5611b111a3e8b6a75f9cf140ebfc88a2400da808384163a68f6ea2b27feae0a2.
# Query part to get results for demonstrationINF
OPTIONAL {
?5611b111a3e8b6a75f9cf140ebfc88a2400da808384163a68f6ea2b27feae0a2
http://data.europa.eu/949/demonstrationINF
?7c9eedbe297dee33d5692bb017576d5f90128c5a57245968861342c5d938bc15_direct.
}
BIND(
COALESCE(?7c9eedbe297dee33d5692bb017576d5f90128c5a57245968861342c5d938bc15_direct,
IF(EXISTS{?5611b111a3e8b6a75f9cf140ebfc88a2400da808384163a68f6ea2b27feae0a2
http://data.europa.eu/949/notYetAvailable
http://data.europa.eu/949/demonstrationINF},
http://data.europa.eu/949/notYetAvailable, ?unbound),
IF(EXISTS{?5611b111a3e8b6a75f9cf140ebfc88a2400da808384163a68f6ea2b27feae0a2
http://data.europa.eu/949/notApplicable
http://data.europa.eu/949/demonstrationINF},
http://data.europa.eu/949/notApplicable, ?unbound),
http://data.europa.eu/949/notData )
AS ?7c9eedbe297dee33d5692bb017576d5f90128c5a57245968861342c5d938bc15).
# Query part to get results for verificationINF
OPTIONAL {
?5611b111a3e8b6a75f9cf140ebfc88a2400da808384163a68f6ea2b27feae0a2
http://data.europa.eu/949/verificationINF
?068c016b70a3e345e79f2c917aa68e82e0a103ed4a2d3a377fc7e6d65298e659_direct.
}
BIND(
COALESCE(?068c016b70a3e345e79f2c917aa68e82e0a103ed4a2d3a377fc7e6d65298e659_direct,
IF(EXISTS{?5611b111a3e8b6a75f9cf140ebfc88a2400da808384163a68f6ea2b27feae0a2
http://data.europa.eu/949/notYetAvailable
http://data.europa.eu/949/verificationINF},
http://data.europa.eu/949/notYetAvailable, ?unbound),
IF(EXISTS{?5611b111a3e8b6a75f9cf140ebfc88a2400da808384163a68f6ea2b27feae0a2
http://data.europa.eu/949/notApplicable
http://data.europa.eu/949/verificationINF},
http://data.europa.eu/949/notApplicable, ?unbound),
http://data.europa.eu/949/notData )
AS ?068c016b70a3e345e79f2c917aa68e82e0a103ed4a2d3a377fc7e6d65298e659).
}
LIMIT 10
For one of the parameters we get the expected results, for the other we are not
getting anything (notData is just the last option of the COALESCE).
If we execute the query with only one of the parameters, the results are the
expected, but not with both at the same time.
We can only get the expected results reordering the statements in the previous
query, like this:
# SPARQL query generated by ERA Search App
SELECT DISTINCT
?e2e8d0ff44169432a9b6a49d415768b6aeb230e6e308eacd14c58203edec7c1e
?5611b111a3e8b6a75f9cf140ebfc88a2400da808384163a68f6ea2b27feae0a2
?7c9eedbe297dee33d5692bb017576d5f90128c5a57245968861342c5d938bc15
?068c016b70a3e345e79f2c917aa68e82e0a103ed4a2d3a377fc7e6d65298e659
FROM http://data.europa.eu/949/graph/rinf
WHERE {
?e2e8d0ff44169432a9b6a49d415768b6aeb230e6e308eacd14c58203edec7c1e a
http://data.europa.eu/949/OperationalPoint.
?e2e8d0ff44169432a9b6a49d415768b6aeb230e6e308eacd14c58203edec7c1e
http://data.europa.eu/949/uopid
?bed82d131276294cde9b33e06fc5540daf5ce0a0ca03c6428b296bff9ff8e95b.
FILTER(lcase(str(?bed82d131276294cde9b33e06fc5540daf5ce0a0ca03c6428b296bff9ff8e95b))
= lcase("DEYBBMO"))
OPTIONALs can be on top of BINDs or the other way around, both cases work, but
not in between.
2- Error in COALESCE division by zero
The following query does not give the expected results.
SELECT ?test
WHERE {
BIND (COALESCE(1/0,3) AS ?test)
}
Virtuoso 22012 Error SR084: Division by 0.
* Related: https://github.com/openlink/virtuoso-opensource/issues/309
* https://github.com/openlink/virtuoso-opensource/issues/140
Do you know if you can have a look on the above issues?
Thank you in advance,
Best regards,
Ghislain
[1] https://data-interop.era.europa.eu/endpoint
Ghislain ATEMEZING
Operational Data Unit
Project Officer
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