SPARQL query on virtual graph

Hi Team,

I am using Stardog 5.3.1 on windows 10. I have faced this issue multiple times (even with stardog 5.2.2). I have created virtual graph with one the SQL server database and have an ontology. I imported ontology files(.rdf) to create a stardog db. Now i have a query which extracts data from virtual graph as well as stardog db. I t works fine. But after some time it stops working. Then i have to do a virtual remove and then virtual add again to make it work. Not sure if this is a common issue. But once i add the exactly same virtual graph again, it starts working as before. Please find the error logs from stardog.log below:

[stardog-user-10] com.complexible.stardog.protocols.http.server.StardogHttpServiceLoader:accept(229): An unexpected exception was handled by the server
org.openrdf.query.QueryEvaluationException: Unable to execute virtual graph query. SQL string: SELECT [Bank].[Bank_ID], [Bank].[Bank_Name], [BankAccountingFinancials].[Total_Asset], [BankAccountingFinancials].[Total_Liabilities], [BankAccountingFinancials].[Total_Equity], [BankAccountingFinancials].[RWA], [BankAccountingFinancials].[Liquidity], [BankAccountingFinancials].[Long_Term_Debt]
FROM [dbo].[Bank]
INNER JOIN [dbo].[BankAccountingFinancials] ON [Bank].[Bank_ID] = [BankAccountingFinancials].[Bank_ID] AND [Bank].[Bank_Name] IS NOT NULL
INNER JOIN [dbo].[BankAccountingFinancials] AS [BankAccountingFinancials0] ON [Bank].[Bank_ID] = [BankAccountingFinancials0].[Bank_ID] AND [BankAccountingFinancials].[Bank_ID] = [BankAccountingFinancials0].[Bank_ID] AND [BankAccountingFinancials].[Total_Asset] = [BankAccountingFinancials0].[Total_Asset] AND [BankAccountingFinancials].[Total_Liabilities] = [BankAccountingFinancials0].[Total_Liabilities] AND [BankAccountingFinancials].[Total_Equity] = [BankAccountingFinancials0].[Total_Equity] AND [BankAccountingFinancials].[RWA] = [BankAccountingFinancials0].[RWA] AND [BankAccountingFinancials].[Liquidity] = [BankAccountingFinancials0].[Liquidity] AND [BankAccountingFinancials].[Long_Term_Debt] = [BankAccountingFinancials0].[Long_Term_Debt]
	at com.complexible.common.rdf.query.IteratorAsTupleQueryResult.hasNext(IteratorAsTupleQueryResult.java:81) ~[stardog-utils-rdf-5.3.1.jar:?]
	at org.openrdf.query.QueryResults.report(QueryResults.java:158) ~[sesame-query-4.1.2.jar:?]
	at org.openrdf.query.resultio.QueryResultIO.writeTuple(QueryResultIO.java:449) ~[sesame-queryresultio-api-4.1.2.jar:?]
	at com.complexible.stardog.protocols.http.server.ProtocolUtils.writeTupleResponse(ProtocolUtils.java:581) ~[stardog-protocols-http-server-5.3.1.jar:?]
	at com.complexible.stardog.protocols.http.server.ProtocolUtils.executeReadQuery(ProtocolUtils.java:488) ~[stardog-protocols-http-server-5.3.1.jar:?]
	at com.complexible.stardog.protocols.http.annex.QueryPanelService.executeQuery(QueryPanelService.java:162) ~[stardog-webconsole-annex-5.3.1.jar:?]
	at com.complexible.stardog.protocols.http.annex.QueryPanelService.post(QueryPanelService.java:112) ~[stardog-webconsole-annex-5.3.1.jar:?]
	at com.stardog.http.server.undertow.jaxrs.ExtractRoutes.lambda$handleIt$5(ExtractRoutes.java:192) ~[stardog-protocols-http-server-5.3.1.jar:?]
	at org.apache.shiro.subject.support.SubjectRunnable.doRun(SubjectRunnable.java:120) [shiro-core-1.3.0.jar:1.3.0]
	at org.apache.shiro.subject.support.SubjectRunnable.run(SubjectRunnable.java:108) [shiro-core-1.3.0.jar:1.3.0]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [?:1.8.0_131]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [?:1.8.0_131]
	at java.lang.Thread.run(Thread.java:748) [?:1.8.0_131]
Caused by: com.complexible.stardog.plan.eval.operator.OperatorException: Unable to execute virtual graph query. SQL string: SELECT [Bank].[Bank_ID], [Bank].[Bank_Name], [BankAccountingFinancials].[Total_Asset], [BankAccountingFinancials].[Total_Liabilities], [BankAccountingFinancials].[Total_Equity], [BankAccountingFinancials].[RWA], [BankAccountingFinancials].[Liquidity], [BankAccountingFinancials].[Long_Term_Debt]
FROM [dbo].[Bank]
INNER JOIN [dbo].[BankAccountingFinancials] ON [Bank].[Bank_ID] = [BankAccountingFinancials].[Bank_ID] AND [Bank].[Bank_Name] IS NOT NULL
INNER JOIN [dbo].[BankAccountingFinancials] AS [BankAccountingFinancials0] ON [Bank].[Bank_ID] = [BankAccountingFinancials0].[Bank_ID] AND [BankAccountingFinancials].[Bank_ID] = [BankAccountingFinancials0].[Bank_ID] AND [BankAccountingFinancials].[Total_Asset] = [BankAccountingFinancials0].[Total_Asset] AND [BankAccountingFinancials].[Total_Liabilities] = [BankAccountingFinancials0].[Total_Liabilities] AND [BankAccountingFinancials].[Total_Equity] = [BankAccountingFinancials0].[Total_Equity] AND [BankAccountingFinancials].[RWA] = [BankAccountingFinancials0].[RWA] AND [BankAccountingFinancials].[Liquidity] = [BankAccountingFinancials0].[Liquidity] AND [BankAccountingFinancials].[Long_Term_Debt] = [BankAccountingFinancials0].[Long_Term_Debt]
	at com.complexible.stardog.plan.eval.operator.impl.ServiceOperatorImpl.computeNext(ServiceOperatorImpl.java:93) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.ServiceOperatorImpl.computeNext(ServiceOperatorImpl.java:30) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.LoopJoin.nextLeft(LoopJoin.java:143) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.LoopJoin.computeNext(LoopJoin.java:176) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.LoopJoin.computeNext(LoopJoin.java:25) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.FilterOp.computeNext(FilterOp.java:83) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.FilterOp.computeNext(FilterOp.java:28) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.SingleProjectionOp.computeNext(SingleProjectionOp.java:82) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.SingleProjectionOp.computeNext(SingleProjectionOp.java:29) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.SliceOp._hasNext(SliceOp.java:87) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.SliceOp.computeNext(SliceOp.java:95) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.SliceOp.computeNext(SliceOp.java:26) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.util.AutoCloseOperator.computeNext(AutoCloseOperator.java:112) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.util.AutoCloseOperator.computeNext(AutoCloseOperator.java:25) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.util.OpBasedBindingSetIteration.computeNext(OpBasedBindingSetIteration.java:110) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.util.OpBasedBindingSetIteration.computeNext(OpBasedBindingSetIteration.java:34) ~[stardog-5.3.1.jar:?]
	at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:143) ~[guava-18.0.jar:?]
	at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:138) ~[guava-18.0.jar:?]
	at com.complexible.common.rdf.query.IteratorAsTupleQueryResult.hasNext(IteratorAsTupleQueryResult.java:77) ~[stardog-utils-rdf-5.3.1.jar:?]
	... 12 more
Caused by: com.complexible.stardog.StardogException: Unable to execute virtual graph query. SQL string: SELECT [Bank].[Bank_ID], [Bank].[Bank_Name], [BankAccountingFinancials].[Total_Asset], [BankAccountingFinancials].[Total_Liabilities], [BankAccountingFinancials].[Total_Equity], [BankAccountingFinancials].[RWA], [BankAccountingFinancials].[Liquidity], [BankAccountingFinancials].[Long_Term_Debt]
FROM [dbo].[Bank]
INNER JOIN [dbo].[BankAccountingFinancials] ON [Bank].[Bank_ID] = [BankAccountingFinancials].[Bank_ID] AND [Bank].[Bank_Name] IS NOT NULL
INNER JOIN [dbo].[BankAccountingFinancials] AS [BankAccountingFinancials0] ON [Bank].[Bank_ID] = [BankAccountingFinancials0].[Bank_ID] AND [BankAccountingFinancials].[Bank_ID] = [BankAccountingFinancials0].[Bank_ID] AND [BankAccountingFinancials].[Total_Asset] = [BankAccountingFinancials0].[Total_Asset] AND [BankAccountingFinancials].[Total_Liabilities] = [BankAccountingFinancials0].[Total_Liabilities] AND [BankAccountingFinancials].[Total_Equity] = [BankAccountingFinancials0].[Total_Equity] AND [BankAccountingFinancials].[RWA] = [BankAccountingFinancials0].[RWA] AND [BankAccountingFinancials].[Liquidity] = [BankAccountingFinancials0].[Liquidity] AND [BankAccountingFinancials].[Long_Term_Debt] = [BankAccountingFinancials0].[Long_Term_Debt]
	at com.complexible.stardog.virtual.vega.VegaServiceQuery.evaluate(VegaServiceQuery.java:168) ~[stardog-virtual-core-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.ServiceOperatorImpl.computeNext(ServiceOperatorImpl.java:79) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.ServiceOperatorImpl.computeNext(ServiceOperatorImpl.java:30) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.LoopJoin.nextLeft(LoopJoin.java:143) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.LoopJoin.computeNext(LoopJoin.java:176) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.LoopJoin.computeNext(LoopJoin.java:25) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.FilterOp.computeNext(FilterOp.java:83) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.FilterOp.computeNext(FilterOp.java:28) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.SingleProjectionOp.computeNext(SingleProjectionOp.java:82) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.SingleProjectionOp.computeNext(SingleProjectionOp.java:29) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.SliceOp._hasNext(SliceOp.java:87) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.SliceOp.computeNext(SliceOp.java:95) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.SliceOp.computeNext(SliceOp.java:26) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.util.AutoCloseOperator.computeNext(AutoCloseOperator.java:112) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.util.AutoCloseOperator.computeNext(AutoCloseOperator.java:25) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.util.OpBasedBindingSetIteration.computeNext(OpBasedBindingSetIteration.java:110) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.util.OpBasedBindingSetIteration.computeNext(OpBasedBindingSetIteration.java:34) ~[stardog-5.3.1.jar:?]
	at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:143) ~[guava-18.0.jar:?]
	at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:138) ~[guava-18.0.jar:?]
	at com.complexible.common.rdf.query.IteratorAsTupleQueryResult.hasNext(IteratorAsTupleQueryResult.java:77) ~[stardog-utils-rdf-5.3.1.jar:?]
	... 12 more
Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: The connection is closed.
	at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(SQLServerException.java:240) ~[mssql-jdbc-6.5.4.jre8-preview.jar:?]
	at com.microsoft.sqlserver.jdbc.SQLServerConnection.checkClosed(SQLServerConnection.java:1025) ~[mssql-jdbc-6.5.4.jre8-preview.jar:?]
	at com.microsoft.sqlserver.jdbc.SQLServerConnection.createStatement(SQLServerConnection.java:3231) ~[mssql-jdbc-6.5.4.jre8-preview.jar:?]
	at com.microsoft.sqlserver.jdbc.SQLServerConnection.createStatement(SQLServerConnection.java:2907) ~[mssql-jdbc-6.5.4.jre8-preview.jar:?]
	at sun.reflect.GeneratedMethodAccessor10.invoke(Unknown Source) ~[?:?]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_131]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_131]
	at org.apache.tomcat.jdbc.pool.ProxyConnection.invoke(ProxyConnection.java:126) ~[tomcat-jdbc-9.0.2.jar:?]
	at org.apache.tomcat.jdbc.pool.JdbcInterceptor.invoke(JdbcInterceptor.java:108) ~[tomcat-jdbc-9.0.2.jar:?]
	at org.apache.tomcat.jdbc.pool.interceptor.AbstractCreateStatementInterceptor.invoke(AbstractCreateStatementInterceptor.java:75) ~[tomcat-jdbc-9.0.2.jar:?]
	at org.apache.tomcat.jdbc.pool.JdbcInterceptor.invoke(JdbcInterceptor.java:108) ~[tomcat-jdbc-9.0.2.jar:?]
	at org.apache.tomcat.jdbc.pool.DisposableConnectionFacade.invoke(DisposableConnectionFacade.java:81) ~[tomcat-jdbc-9.0.2.jar:?]
	at com.sun.proxy.$Proxy43.createStatement(Unknown Source) ~[?:?]
	at com.complexible.stardog.virtual.vega.VegaServiceQuery.evaluate(VegaServiceQuery.java:155) ~[stardog-virtual-core-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.ServiceOperatorImpl.computeNext(ServiceOperatorImpl.java:79) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.ServiceOperatorImpl.computeNext(ServiceOperatorImpl.java:30) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.LoopJoin.nextLeft(LoopJoin.java:143) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.LoopJoin.computeNext(LoopJoin.java:176) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.LoopJoin.computeNext(LoopJoin.java:25) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.FilterOp.computeNext(FilterOp.java:83) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.FilterOp.computeNext(FilterOp.java:28) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.SingleProjectionOp.computeNext(SingleProjectionOp.java:82) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.SingleProjectionOp.computeNext(SingleProjectionOp.java:29) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.SliceOp._hasNext(SliceOp.java:87) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.SliceOp.computeNext(SliceOp.java:95) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.impl.SliceOp.computeNext(SliceOp.java:26) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.util.AutoCloseOperator.computeNext(AutoCloseOperator.java:112) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.util.AutoCloseOperator.computeNext(AutoCloseOperator.java:25) ~[stardog-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.tryToComputeNext(AbstractSkippingIterator.java:143) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.common.collect.AbstractSkippingIterator.hasNext(AbstractSkippingIterator.java:130) ~[stardog-utils-common-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.util.OpBasedBindingSetIteration.computeNext(OpBasedBindingSetIteration.java:110) ~[stardog-5.3.1.jar:?]
	at com.complexible.stardog.plan.eval.operator.util.OpBasedBindingSetIteration.computeNext(OpBasedBindingSetIteration.java:34) ~[stardog-5.3.1.jar:?]
	at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:143) ~[guava-18.0.jar:?]
	at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:138) ~[guava-18.0.jar:?]
	at com.complexible.common.rdf.query.IteratorAsTupleQueryResult.hasNext(IteratorAsTupleQueryResult.java:77) ~[stardog-utils-rdf-5.3.1.jar:?]
	... 12 m

Thank you!

Hi Smrati,

The log shows:

Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: The connection is closed.

Was there an exception on a separate query prior to this? Is there a network problem between the Stardog server and the SQL server? What are your connection pool settings? It’s possible the connection was closed due to a timeout.

Jess

Unfortunately this was the only query i tried.
I am not sure if the connection was closed, as i just removed the virtual graph and created again and it worked fine. This has happened more than once.
What are your connection pool settings? : i use just the basic once: url, username, password and driver.
I think someone already suggested me this and i tried increasing maxWait but nothing changed.

Thanks!

Is there anything else that i can change for connection pool settings?
or any other settings in general?

Thanks

The virtual graph configuration options file also accepts tomcat connection pool options. If you’re asking I’m guessing that you don’t have any set.

https://www.stardog.com/docs/#_virtual_graph_configuration_options

“…connection pool configuration of the built-in Tomcat connection pool are allowed…”

Yes, i understand that. I got this answer earlier. I tried maxWait as mentioned in:
https://tomcat.apache.org/tomcat-9.0-doc/jdbc-pool.html#Common_Attributes
as suggested by someone. But it did not work for me. I meant is there anything other than this that i can change and try!

Thank you!

maxWait is specifically concerned with timing out a request for a connection when all connections are in use. Perhaps setting testOnBorrow will solve the issue for you.

Jess

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