[Mulgara-general] [mulgara-general] TuplesException in an ITQL count operation

Mon Jan 28 22:06:03 UTC 2013

This looks like a problem I've had before where empty results lose their
columns names. If that's the case, then I can work around it. However,
there should be a single row answer for this kind of query, even if it's
just a count of 0, so that may not be the problem.

Do you know how large the result set is in this case? I'm presuming it's
not empty?

Paul

On Mon, Jan 28, 2013 at 3:05 PM, Rich d'Rich <rich.d.rich at gmail.com> wrote:

> We're using Mulgara 2.1.4 (embedded in Fedora 3.5) and getting an
> occasional issue on our production repo.
>
> The problem manifests when we execute a query of the form:
> *select count(subquery) from <#ri> where $a $b $c*
>
> Normally this query runs fine, but occasionally it will fail with a
> TuplesException (see log below). After that, each call to that query will
> fail with the same exception.
> Executing "subquery" on its own works, and the problem is cleared by a
> restart of the (tomcat) container.
>
> It looks like the state/query is being cached such that any further
> textually identical queries trigger the bug?
>
> Any suggestions would be welcomed.
>
> *LOG:*
> ERROR 2012-12-11 09:31:24.075 [http-8080-9] (RISearchServlet) Unexpected
> error servicing API-A request
> org.trippi.TrippiException: Transaction error
>         at
> org.trippi.impl.mulgara.MulgaraTupleIterator.<init>(MulgaraTupleIterator.java:27)
> [trippi-mulgara-1.5.4.jar:na]
>         at
> org.trippi.impl.mulgara.MulgaraSession.query(MulgaraSession.java:157)
> [trippi-mulgara-1.5.4.jar:na]
>         at
> org.trippi.impl.base.ConcurrentTriplestoreReader.findTuples(Unknown Source)
> [trippi-core-1.5.4.jar:na]
>         at
> org.fcrepo.server.resourceIndex.ResourceIndexImpl.findTuples(ResourceIndexImpl.java:280)
> [fcrepo-server-3.5.jar:na]
>         at
> org.fcrepo.server.resourceIndex.ResourceIndexModule.findTuples(ResourceIndexModule.java:312)
> [fcrepo-server-3.5.jar:na]
>         at org.trippi.server.TrippiServer.find(Unknown Source)
> [trippi-core-1.5.4.jar:na]
>         at org.trippi.server.http.TrippiServlet.doFind(Unknown Source)
> [trippi-core-1.5.4.jar:na]
>         at org.trippi.server.http.TrippiServlet.doGet(Unknown Source)
> [trippi-core-1.5.4.jar:na]
>         at
> org.fcrepo.server.access.RISearchServlet.doGet(RISearchServlet.java:101)
> [fcrepo-server-3.5.jar:na]
>         at org.trippi.server.http.TrippiServlet.doGet(Unknown Source)
> [trippi-core-1.5.4.jar:na]
>        at org.trippi.server.http.TrippiServlet.doPost(Unknown Source)
> [trippi-core-1.5.4.jar:na]
>         at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
> [servlet-api.jar:na]
> [ tomcat stuff ]
>
> Caused by: org.mulgara.query.TuplesException: Transaction error
>         at
> org.mulgara.resolver.MulgaraInternalTransaction.execute(MulgaraInternalTransaction.java:657)
> [mulgara-core-2.1.4.jar:na]
>         at
> org.mulgara.resolver.TransactionalAnswer.getObject(TransactionalAnswer.java:86)
> [mulgara-core-2.1.4.jar:na]
>         at org.trippi.impl.mulgara.RowGroup.initialize(RowGroup.java:45)
> [trippi-mulgara-1.5.4.jar:na]
>         at org.trippi.impl.mulgara.RowGroup.<init>(RowGroup.java:33)
> [trippi-mulgara-1.5.4.jar:na]
>         at
> org.trippi.impl.mulgara.CollapsedAnswer.initialize(CollapsedAnswer.java:74)
> [trippi-mulgara-1.5.4.jar:na]
>         at
> org.trippi.impl.mulgara.CollapsedAnswer.<init>(CollapsedAnswer.java:58)
> [trippi-mulgara-1.5.4.jar:na]
>         at
> org.trippi.impl.mulgara.MulgaraTupleIterator.<init>(MulgaraTupleIterator.java:24)
> [trippi-mulgara-1.5.4.jar:na]
>         ... 35 common frames omitted
>
> Caused by: org.mulgara.query.MulgaraTransactionException: Transaction
> rollback triggered
>         at
> org.mulgara.resolver.MulgaraInternalTransaction.implicitRollback(MulgaraInternalTransaction.java:516)
> [mulgara-core-2.1.4.jar:na]
>         at
> org.mulgara.resolver.MulgaraInternalTransaction.execute(MulgaraInternalTransaction.java:652)
> [mulgara-core-2.1.4.jar:na]
>         ... 41 common frames omitted
>
> Caused by: *org.mulgara.query.TuplesException: No such variable $k0 in
> tuples [] *(class org.mulgara.store.tuples.UnconstrainedTuples)
>         at
> org.mulgara.store.tuples.AbstractTuples.getColumnIndex(AbstractTuples.java:363)
> [mulgara-core-2.1.4.jar:na]
>         at
> org.mulgara.resolver.GlobalizedAnswer.getColumnIndex(GlobalizedAnswer.java:141)
> [mulgara-core-2.1.4.jar:na]
>         at
> org.mulgara.resolver.SubqueryAnswer.getObject(SubqueryAnswer.java:199)
> [mulgara-core-2.1.4.jar:na]
>         at
> org.mulgara.resolver.TransactionalAnswer$1.execute(TransactionalAnswer.java:88)
> [mulgara-core-2.1.4.jar:na]
>         at
> org.mulgara.resolver.MulgaraInternalTransaction.execute(MulgaraInternalTransaction.java:649)
> [mulgara-core-2.1.4.jar:na]
>         ... 41 common frames omitted
>
> The exact queries are:
> *FAILS:* *select count(select $subject $title $type *
> *from <#ri> *
> *where $subject <http://quakestudies.canterbury.ac.nz#isPartOf>
> <info:fedora/qsr-object:296> and $subject <
> http://purl.org/dc/elements/1.1/type> $type *
> *and $subject <http://purl.org/dc/elements/1.1/title> $title and $subject
> <http://purl.org/dc/elements/1.1/type> 'part' *
> *and (($subject <http://quakestudies.canterbury.ac.nz#needEffectiveRole>
> $rolepid and ($rolepid <http://quakestudies.canterbury.ac.nz#hasMemberUser>
> <info:fedora/anon> *
> *or $rolepid <http://purl.org/dc/elements/1.1/title> 'Public')))) *
>
> from <#ri> where $a $b $c
>
> *WORKS:* *select $subject $title $type *
> *from <#ri> *
> *where $subject <http://quakestudies.canterbury.ac.nz#isPartOf>
> <info:fedora/qsr-object:296> and $subject <
> http://purl.org/dc/elements/1.1/type> $type *
> *and $subject <http://purl.org/dc/elements/1.1/title> $title and $subject
> <http://purl.org/dc/elements/1.1/type> 'part' *
> *and (($subject <http://quakestudies.canterbury.ac.nz#needEffectiveRole>
> $rolepid and ($rolepid <http://quakestudies.canterbury.ac.nz#hasMemberUser>
> <info:fedora/anon> *
> *or $rolepid <http://purl.org/dc/elements/1.1/title> 'Public')))*
>
> Also, I have a copy of the resourceIndex folder before I restarted the
> server.
>
> Cheers,
> Richard
>
>
> _______________________________________________
> Mulgara-general mailing list
> Mulgara-general at mulgara.org
> http://lists.mulgara.org/mailman/listinfo/mulgara-general
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mulgara.org/pipermail/mulgara-general/attachments/20130128/ddfe58ab/attachment-0001.html>