[ovs-dev] RFC: OVN database options

Ben Pfaff blp at ovn.org
Fri Mar 11 16:07:39 UTC 2016


On Fri, Mar 11, 2016 at 09:58:18AM +0100, Ivan Kelly wrote:
> > Zookeeper transactions can be isolated depending on what level of
> > isolation you need.
> > A setData on a node operation can contain a version, so that it fails
> > if that node has changed since the version. This means with a multi[1]
> > of setData operations, you can effectively get a snapshot isolation
> > level of isolation. For serializable, you could probably shoehorn it
> > in by rewriting all nodes that you've written.
> Thinking about this more, and refreshing my cache on isolation levels,
> I realized that zookeeper doesn't in fact offer SI, since reads are
> done one at a time, and the state in the database may change between
> reads to the same node. So zookeeper offers "Read committed" rather
> than SI.

Just to make sure, does this means that a Zookeeper client cannot read a
consistent snapshot of the entire database?



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