XpoWorkflowInstance filling up database

By default, workflow instances are deleted on completion. Since the DevExpress.Workflow.Xpo.XpoWorkflowInstance persistent class has deferred deletion enabled, the records are not physically deleted from the database. These soft-deleted records can fully be removed by using a separate tool that will call the DevExpress.Xpo.Session.PurgeDeletedObjects() method. This administrative tool can be concerned with not only about removal of workflow data, but also about other persistent classes with deferred deletion. You can run it on a schedule, if you wish. The XpoTrackingRecord table can also be concerned with this for the same reason.

There are also alternative options:

1. Implementing a DevExpress.Workflow.Xpo.XpoWorkflowInstance descendant mapped to the parent table and decorated with the DeferredDeletion(false) attribute.
2. Implement custom code directly in the workflow service application that will remove unwanted data from required tables, e.g.:

Code
public class WorkflowServerStarter : MarshalByRefObject {  
        ...  
        private void Start_(string connectionString, string applicationName) {  
            ...  
            server.CustomizeHost += delegate(object sender, CustomizeHostEventArgs e) {  
                e.WorkflowInstanceStoreBehavior.WorkflowInstanceStore.RunnableInstancesDetectionPeriod = TimeSpan.FromSeconds(2);  
                e.WorkflowInstanceStoreBehavior.WorkflowInstanceStore.InstanceComplete += new EventHandler<DevExpress.Workflow.Store.InstanceEventArgs>(WorkflowInstanceStore_InstanceComplete);  
            };  
            ...  
        }  
        void WorkflowInstanceStore_InstanceComplete(object sender, DevExpress.Workflow.Store.InstanceEventArgs e) {  
            if (e.Status == System.Activities.ActivityInstanceState.Closed) {  
                var fi = typeof(DevExpress.Workflow.Store.WorkflowInstanceStore).GetField("objectSpaceProvider", System.Reflection.BindingFlags.Instance| System.Reflection.BindingFlags.NonPublic);  
                IObjectSpaceProvider provider = (IObjectSpaceProvider)fi.GetValue(sender);  
                using (var os = provider.CreateObjectSpace()) {  
                    var list = os.GetObjects<DevExpress.Workflow.Xpo.XpoTrackingRecord>(new BinaryOperator("InstanceId", e.Id));  
                    os.Delete(list);  
                    os.CommitChanges();  
                    ((XPObjectSpace)os).Session.PurgeDeletedObjects();  
                }  
            }  
        }  
        ...  
      }