Using a second query while scrolling causes the ScrollableResults to be closed.
Minimal example:
{code:java}public static void main(String[] args)
{
EntityManager em = getEntityManager();
// Query to be used while scrolling. Can be Native or not,
// it doesn't seem to matter what the query is. ( I just wanted to keep it simple)
Query qExtra = em.createNativeQuery("SELECT 1");
Query q = em.createQuery("SELECT row FROM User row");
q.setMaxResults(10);
@SuppressWarnings("rawtypes")
org.hibernate.query.Query hibernateQuery = q.unwrap(org.hibernate.query.Query.class);
ScrollableResults sr = hibernateQuery.scroll();
while(sr.next())
{
// Comment this query out and function finishes normally
qExtra.getSingleResult();
}
em.close();
}{code}
Perhaps I am not supposed to unwrap the JPA2 query like that?
WIth Hibernate 5.1.0 and the following code to obtain a ScrollableResults, the example code works as expected:
{code:java}org.hibernate.Query query = ((org.hibernate.jpa.internal.QueryImpl)q).getHibernateQuery();
ScrollableResults sr = query.scroll(ScrollMode.FORWARD_ONLY);{code}
However, running 5.4.18, it does not appear to matter what query I issue inside the loop, it will close the result set.
The resulting exception from 5.4.18:
{noformat}Exception in thread "main" org.hibernate.exception.GenericJDBCException: could not advance using next()
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:47)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:113)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:99)
at org.hibernate.internal.ScrollableResultsImpl.convert(ScrollableResultsImpl.java:70)
at org.hibernate.internal.ScrollableResultsImpl.next(ScrollableResultsImpl.java:105)
at Test.main(Test.java:???)
Caused by: java.sql.SQLException: You can't operate on a closed ResultSet!!!
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:118)
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:77)
at com.mchange.v2.c3p0.impl.NewProxyResultSet.next(NewProxyResultSet.java:691)
at org.hibernate.internal.ScrollableResultsImpl.next(ScrollableResultsImpl.java:100)
... 1 more
Caused by: java.lang.NullPointerException
at com.mchange.v2.c3p0.impl.NewProxyResultSet.next(NewProxyResultSet.java:685)
... 2 more{noformat}
Thanks for any help\!
Addendum:
I have tested the following code using the JPA2 getResultStream(), and it also produces the same exception:
{noformat}public static void main(String[] args)
{
EntityManager em = EntityManagerSingleton. getEntityManager();
Query qExtra = em.createNativeQuery("SELECT 1");
Query q = em.createQuery("SELECT row FROM User row");
q.getResultStream().forEach(row -> { qExtra.getSingleResult(); });
em.close();
}{noformat}
The exception from using getResultStream():
{noformat}Exception in thread "main" org.hibernate.exception.GenericJDBCException: could not advance using next()
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:47)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:113)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:99)
at org.hibernate.internal.ScrollableResultsImpl.convert(ScrollableResultsImpl.java:70)
at org.hibernate.internal.ScrollableResultsImpl.next(ScrollableResultsImpl.java:105)
at org.hibernate.query.internal.ScrollableResultsIterator.hasNext(ScrollableResultsIterator.java:33)
at java.util.Iterator.forEachRemaining(Iterator.java:115)
at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:580)
at org.hibernate.query.spi.StreamDecorator.forEach(StreamDecorator.java:155)
at Tester.main(Tester.java)
Caused by: java.sql.SQLException: You can't operate on a closed ResultSet!!!
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:118)
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:77)
at com.mchange.v2.c3p0.impl.NewProxyResultSet.next(NewProxyResultSet.java:691)
at org.hibernate.internal.ScrollableResultsImpl.next(ScrollableResultsImpl.java:100)
... 6 more
Caused by: java.lang.NullPointerException
at com.mchange.v2.c3p0.impl.NewProxyResultSet.next(NewProxyResultSet.java:685)
... 7 more{noformat} |
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