Re: Rados multi-object transaction use cases

[Yehuda Sadeh-Weinraub <yehuda@redhat.com>]

----- Original Message -----
> From: "Samuel Just" <sjust@redhat.com>
> To: "ceph-devel" <ceph-devel@vger.kernel.org>
> Sent: Friday, June 12, 2015 3:15:02 PM
> Subject: Rados multi-object transaction use cases
> 
> In the Infernalis CDS, we had a session on RADOS multi-object transactions.
> I'd like to continue the discussion at the upcoming Jewel CDS.  I thought
> I'd prime the discussion by asking: if librados supported multi-object read
> and write transactions, what would you use them for?  Some idea of use cases
> would be valuable when considering things like deadlock coping strategies.

Here are a few for rgw:
 - update bucket index when creating / modifying / deleting an object
 - store multiple metadata objects atomically: e.g., user info + user access keys + user email (currently not atomic)
 - store bucket entry point + bucket instance info atomically
 - creating a bucket and adding it to the user's list of buckets

Yehuda