Leopard syncing

  • Hi,

    It seemed during the "Tiger era" that we were encouraged to use the
    truth database to keep common data types synced ( address book,
    calendar, bookmarks, etc), but not our own data types.  This made
    sense, as we would be storing all the same data twice - once in each
    format - not to mention the unknown number of times it would also
    exist on additional synced computers.  With Leopard, it seems that we
    are now being encouraged to use Core Data and the new very handy sync
    features to give our apps the ability to use the sync engine and stay
    synchronized across multiple machines.  This sounds both wonderful
    and wasteful.  The main question is this -- am I correct about this
    interpretation?  Are we now encouraged to put copies of our data into
    the truth database?  Is there no concern that it will become HUGE?  I
    don't care, if you feel the truth database is set up to  handle it.

    Also, if we use the truth database to stay synced, how does that work
    with 3 computers, say one at home, one at work and a laptop.  I'd
    like to keep them all synced, so how many copies of the data exist?
    Doesn't each machine have a truth database?  Whose rules?  There is a
    mention of designating a "master truth database," but it isn't clear
    how you might do that, unless it is just a procedural thing the user
    needs to be aware of.

    Thanks,
    Denise
  • On Dec 12, 2007, at 3:28 PM, Denise Eatherly wrote:

    > It seemed during the "Tiger era" that we were encouraged to use the
    > truth database to keep common data types synced ( address book,
    > calendar, bookmarks, etc), but not our own data types.  This made
    > sense, as we would be storing all the same data twice - once in each
    > format - not to mention the unknown number of times it would also
    > exist on additional synced computers.

    Since when? No one was ever discouraged from making their own schema.

    > The main question is this -- am I correct about this
    > interpretation?  Are we now encouraged to put copies of our data
    > into the truth database?

    If you want to synchronize them across computers, then you can
    certainly do it, and you have been able to since Tiger.

    > Is there no concern that it will become HUGE?

    It will, oh, it will.

    > I don't care, if you feel the truth database is set up to  handle it.

    The problem we've run into is Sync Services works best when individual
    records are small (less than a megabyte per record) and few (less than
    10,000). We've run into some users who are trying to use Sync Services
    for stuff that is _way_ beyond what it was designed to handle, e.g.
    30,000+ contact records, 10+ megabyte NSData blobs, and then become
    angry when suddenly sync sessions take hours or crash because either
    the server or client hit the 4 GB memory limit. I assume all of the
    limits have been lifted in the 64-bit version, which we currently
    cannot use due to some dependencies on other things.

    > Also, if we use the truth database to stay synced, how does that
    > work with 3 computers, say one at home, one at work and a laptop.
    > I'd like to keep them all synced, so how many copies of the data
    > exist?

    Three.

    > Doesn't each machine have a truth database?

    Not each "machine", each user account.

    > Whose rules?  There is a mention of designating a "master truth
    > database," but it isn't clear how you might do that, unless it is
    > just a procedural thing the user needs to be aware of.

    The master database is already in ~/Library/Application Support/
    SyncServices.

    Nick Zitzmann
    <http://www.chronosnet.com/>
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