Instead of building patron reading history off of the issues and old_issues tables, store the information in a separate table. This gives the following advantages: 1) The history of having checked out the item will persist after the item or title is deleted, or issuing history is anonymized/deleted. 2) The patron can more strictly govern the management of their reading history without impacting the library's circulation history RFC: http://wiki.koha-community.org/wiki/Patron_Reading_History_Separate_from_Issues_RFC