I'm afraid i've come up against a brick wall. I've tried to query a MS SQL2005 with two large tables, from iReports 3.5 on both an XP and Linux machine, and I get the Java Heap Space error. I've used two versions of the SQLJDBC 1.1.1501 and 2.0.1803, and get the same problem. Given that Jasperreports is java based, I'd assume that the developers have some idea?? Code:Query error Message: net.sf.jasperreports.engine.JRException: SQL problems:The system is out of memory. Use server side cursors for large result sets:Java heap space. Result set size:811,311,558. JVM total memory size:532,742,144.Level: SEVEREStack Trace:SQL problems: The system is out of memory. Use server side cursors for large result sets:Java heap space. Result set size:811,311,558. JVM total memory size:532,742,144. com.jaspersoft.ireport.designer.data.fieldsproviders.SQLFieldsProvider.getFields(SQLFieldsProvider.java:360) com.jaspersoft.ireport.designer.connection.JDBCConnection.readFields(JDBCConnection.java:479) com.jaspersoft.ireport.designer.wizards.ConnectionSelectionWizardPanel.validate(ConnectionSelectionWizardPanel.java:126) org.openide.WizardDescriptor$6.run(WizardDescriptor.java:1268) org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:561) org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:986