I used db/jbpm.jpdl.mssql.sql file extracted from jbpm-jpdl-suite-3.2.GA.zip to create the jbpm database. There is a unique constraint on column group (KEY_, PROCESSDEFINITION_) on table JBPM_PROCESSDEFINITION, but the key property of process instance object is set to null by default, so inserting more than one process instance of a process definition into JBPM_PROCESSDEFINITION will dissatisfy this unique constraint. How to solve this problem? Can I remove the unique constraint?
Please have a look at this related JIRA entry, as this might shed some light on the usage of constraints:
http://jira.jboss.com/jira/browse/JBPM-913