Hi Hugh
I have looked at the source for the JDBC driver and the error seem to be
in the VirtuosoResultSet.getMoreResults() method
The member variable more_result is always set to true at the end of
the method regardless of any processing logic. (see source pasted
below).
I have to say the quality of the source is a bit worrying (to say the
least) -there also seems to be a lack of test coverage (unit tests)
For example, there is a openlink.util.Vector class being used which
seems to be a copy of the Java 1.1 Vector except the synchronisation has
been omitted. Why are the Collection classes not being used ?
The code I have looked at (the HEAD of the trunk in CVS), only seems to
have a (source) package for the JDBCType4 driver, but the comments
throughout the code refer to JDBC2. Also compiler directives are being
used etc etc...
Sorry to be so negative,
regards Paul
/**
* Method uses to get next rows of this result set.
*
* @exception virtuoso.jdbc2.VirtuosoException An internal error
occurred
*/
protected void getMoreResults() throws VirtuosoException
{
synchronized (statement.connection)
{
//System.err.println ("getMoreResults");
// Reset some flags
rowIsDeleted = rowIsUpdated = rowIsInserted = is_complete =
false;
currentRow = 0;
// Delete older rows
if(rows == null)
rows = new openlink.util.Vector(20);
else
rows.removeAllElements();
// One more time
process_result();
more_result = true;
//System.err.print ("more_results: after process : rows :");
//System.err.println (rows.toString());
}
}
From: Hugh Williams [mailto:hwilli...@openlinksw.com]
Sent: 23 June 2009 15:36
To: Jem Rayfield
Cc: Sonja Nevitt; virtuoso-users@lists.sourceforge.net List; Paul Wilton
Subject: Re: JDBC feature
Hi Jem,
We are looking into this and shall report back with our findings ...
Best Regards
Hugh Williams
Professional Services
OpenLink Software
Web: http://www.openlinksw.com
Support: http://support.openlinksw.com
Forums: http://boards.openlinksw.com/support
On 23 Jun 2009, at 15:18, Jem Rayfield wrote:
Hi,
We are experience an interesting feature with the availible JDBC
drivers. (JDBC3 and JDBC4).
(Driver version: 05.10.3038. Transaction isolation level : 4.)
When an SQL invocation returns zero results we get into an infinte loop
situation.
We are using iBatis as an ORM mapping tool.
iBatis checks the first result set which returns nothing. At this point
we are in good shape. After which iBatis contiunes to check further
result sets to ensure that there are no other results.
However at this point the following is always true within the Driver
code base:
VirtuosoPreparedStatement .vresultset.more_result=true
VirtuosoPreparedStatement.getMoreResults()
iBatis in turn continues iterating and checking empty result sets. The
produces an infinte loop and a hanging process.
The driver should return FALSE as there are no results.
The query being invoked is as follows:
select * from DB.METADATA.STORY where id in (
SPARQL PREFIX md:
<http://nolapps34.newsonline.tc.nca.bbc.co.uk:8890/md#
<http://nolapps34.newsonline.tc.nca.bbc.co.uk:8890/md> >
SELECT ?id FROM
<http://nolapps34.newsonline.tc.nca.bbc.co.uk:8890/md#
<http://nolapps34.newsonline.tc.nca.bbc.co.uk:8890/md> >
WHERE {
?x md:id ?id .
?x md:title 'SOME STORY'
}
)
FYI:
The version of iBatis is as follows: iBatis version (2.3.4.726) (latest
stable).
The iBatis line of code which checks the resultset status is as follows:
SqlExecutor.java line 354
Can you let us have your thoughts as this is a real pain.
FYI: We are unable to use hibernate as there is currently no hibernate
dialect and wish to use an ORM tool.
Thanks
Jem
http://www.bbc.co.uk
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