[Ietf-caldav] polling

[Dan Winship]

On Tue, 2004-08-17 at 10:04 -0700, Lisa Dusseault wrote:
> There's another way to track deleted items, which is tombstones, which 
> I prefer to IMAP-style sequence numbers.   You'd give everything UIDs, 
> as in your scheme, and mark some UIDs as deleted since timestamp T.  I 
> believe tombstones are much easier to track for both client and server 
> in many situations, because each item has fewer dependencies on other 
> items.

I agree that that's simpler, but you'd need to keep the tombstone around
forever, right? So the amount of storage space used by the collection is
proportional to the total number of items that have ever been in it. Or
alternatively, if you do garbage-collect the tombstones after a while,
then there's an upper limit on how long the client can go between
connections and still be able to incrementally resync afterwards.
Whereas with my suggestion, the total storage space used stays
proportional to the current size of the collection, and the client can
resync at any time and only need to download an amount of data
proportional to the number of changes made since the last sync.

-- Dan