Delete Old/Terminated Workflow from DB

Hi all,

I would like to delete old (Completed, Terminated) workflow related data (AFCOMMENT & AFDOCUMENT) from the idmuserappdb.
Based on ideas shared in /cyberres/idm/f/idm_discussion/439104/re-how-to-delete-old-workflows-tasks-from-identity-manager

and also as suggestions in   /cyberres/idm/f/idm_discussion/429306/user-app---request-status---remove-old-tasks and other references included.

I checked from iManager, and confirmed the number of process having Terminated status, are over 1000.

I have reduced the Completed Process Timeout (day) to 10 days from the default 120 days. The cleanup interval was changed to 5 hours (in UA Workflow Engine & Cluster config).
Saved, and restarted tomcat, but the size have not changed in the DB over the past 48 hours.

What ought to be the  indications that the Engine has performed the cleanup ?  Could  I be missing any step ?

The size of the AFCOMMENT and AFDOCUMENT tables in the idmuserappdb & igaworkflowdb remain the same (over 4.5GB & 2.4GB respectively) in the DB,
but I would like it to be reduced to below 1.5 GB or as small as possible,
because the previous UserApp upgrade (4.6.4 -- > 4.8) I did involving importing schema/tables into an igaworkflowdb in different server (ORACLE schema restriction),
lasted over 6 hours due to the huge size of AFCOMMENT and AFDOCUMENT.

I would like to reduce the size of the AFCOMMENT and AFDOCUMENT tables, to probably cut down the hours of importation during the next upgrade case.

Any ideas, pointers, clues would be greatly appreciated.