It's just for testing and debug purposes and it's going away anyway.

Sometimes I do want it to send everything again - for instance, if 
something happened to the db in my phone and I want to get everything 
again.



Since you are saying that this is not the intended function of 
deleting the sync history (what is it for then, by the way?), perhaps 
this bug should be changed to a feature request to have an option for 
slow sync.

It's not touching the map table at all, it's only deleting the 
synchronization anchors. You don't want to delete the map, because it 
would cause duplicate entries during the next sync.

When the sync history is deleted, I would expect a slow sync to 
happen. This is not what happens. In fact, nothing does.



I get many line like this in the log:



DEBUG:  SQL Query by SyncML_Backend_Horde::_getCuid(): SELECT 
syncml_cuid FROM horde_syncml_map WHERE syncml_syncpartner = ? AND 
syncml_db = ? AND syncml_ui$

DEBUG:  Added to server from client during SlowSync: 
20080330104002.@server.org ignored



and finally:



DEBUG:  Sending 0 server changes for client URI ./calendar



I have also looked in the DB itself, and it still contains a lot of 
data in the horde_syncml_map