Hi Paul,
Thanks for the additional information. I have passed your comments on
to development who are already looking into this, and shall report
back when I have an updated from them ...
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 24 Jun 2009, at 10:44, Paul Wilton wrote:
Hi Hugh
The VirtusosStatement.getMoreResults() method does not meet the
contract of the Statement interface API.
I don’t think it handles multiple results at all, and always
returns true .
The contract of the Statement interface method Statement.
getMoreResults() states :
“Returns: true if the next result is a ResultSet object; false if
it is an update count or there are no more results”
http://java.sun.com/j2se/1.4.2/docs/api/java/sql/
Statement.html#getMoreResults()
the code in VirtusosStatement.getMoreResults() does the following:
{....
vresultSet.getMoreResults(); // this always returns true (see
my previous email)
return true; // this method returns true regardless
... }
Thus any implementing code which need to handle multiple result
sets (ie Hibernate/iBatis) is going to fail.
Regards
Paul
From: Paul Wilton [mailto:paul.wil...@bbc.com]
Sent: 24 June 2009 09:54
To: Hugh Williams; Jem Rayfield
Cc: Sonja Nevitt; Julian Everett; virtuoso-users@lists.sourceforge.net
Subject: Re: [Virtuoso-users] JDBC feature
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#>
SELECT ?id FROM <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
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