[horde] cleanup of horde_histories when removal of calendar or removeUserData()

[Steffen]

Hi,

after I've setup Horde 5 (horde 5.1.6 stable), I'm testing to remove user 
data from it currently.

It looks like many - if not all - entries remain in horde_histories, if I 
use the horde-remove-user-data script to remove an user. Actually for 
testing purpose I have removed all users from my DB. :-)

If I remove a calendar, all events get a history item with action 
"delete". However, if the calendar is gone, which parts / functions will 
access that item ever? Because the "add" log entry does not contain any 
data, you cannot rebuilt a deleted event with that information.

I suppose that applies to any other folder-like object (container) as 
well, such as notepads, addressbooks,& tasks.

If one removes an user with removeUserData() or the horde-remove-user-data 
script, those entries remain as well. And because the container is gone, 
you cannot know, to which user the entry belongs to. history_who contains 
the deleter, which probably is an admin, e.g. for the script.

My question is: would it harm, if one removes the history items, when the 
parent container (calendar, address book, ...) of the object is removed?

Or if the immediate removal is not appropriate, could the history maintain 
a field like "timestamp when parent container got removed", so one can 
run a database cleanup with this information on a regular base?

I suppose to let each Horde app handle the cleanup itself is required, 
because the naming convention of object_uid is app depended and you cannot 
guess how to verify the existance of the parent from the object_uid value 
with an outside script for sure.

-- 
Steffen