read and restore deleted record

Hi all..

Start from vacuum feature information from PGSQL helps documentation, it telling me that Postgresql didn’t delete data permanently when we execute delete command, it just made the data invalid. By following this email archive :

http://archives.postgresql.org/pgsql-admin/2005-01/msg00176.php

I could get the table files, my question is, how could I read again the deleted record from that files.

Thank you and best regards,

Soultani