If you are doing a new install of AX 2012, you should make sure to turn off Keep update objects in the license configuration form. 

The Keep update objects configuration keys are tied to objects in the SQL database with a prefix of DEL_.

The DEL_ tables and DEL_ fields are some of the few objects that are dropped from the SQL server database in AX 2012 when a configuration key is disabled.  Un-marking the keep update objects can help with the size of the database and with performance.

See blog http://blogs.msdn.com/b/emeadaxsupport/archive/2008/11/03/performance-sysdeletedobjects40-keep-updated-objects.aspx

During a new install of Dynamics AX 2012 you may see issues when you leave the keep update objects marked under the Administration node of the License Configuration form. 

You may encounter errors about a missing
DEL_GENERATIONEXECUTIONPLAN column. The system also tries to insert error messages into the SYSTRACETABLESQL table and hits another error because the SYSTRACETABLESQL is not yet synchronized and the DEL_CREATEDTIME column is missing.

In a new install you can work around this issue in two ways:

  1. Open the developer workspace and synchronize the database and then go back and finish the initialization check.
  2. In the License configuration form do not mark the Keep Update objects, which would only be needed to upgrade from earlier versions of Dynamics AX.

Another issue you may encounter is in the Workflow Configuration editor, where you can create conditional statements based on the fields in the workflow documents you are working with.

For instance you can create a conditional statement on the Purchase requisition lines category field

If you are in an environment where the update objects are turned on, you will get different conditional statements to choose from and may be incorrect based on the field type.  In this example all the DEL_ fields will still be visible and will show up in the Query datasource if it is set to display all the table fields, and eventually in the Condition Editor UI. Now, one of the DEL_ fields (PurchReqLine.DEL_ProductGroupId) has the same display name of “Category” which conflicts with PurchReqLine.ProcurementCategory field. What is being surfaced in the Condition Editor is the display name corresponding to the DEL_ProductGroupID and not ProcurementCategory. To resolve this issue you would have to turn off the update license configuration keys and restart the server and then you should be seeing the desired behavior.

If you have completed your AX 2012 upgrade and gone live and you encounter issues after the upgrade, using the DEL_ tables and DEL_ fields can be critical in determining root cause of issues for upgraded customers.  If you have been running successfully for a reasonable timeframe (three months for example), then you can consider turning off the configuration key.