Amre commented on ZOOKEEPER-646:

This would definitely be a useful feature. However, we have a little bit 
different motivation for the namespace partitioning.

We've been using Zookeeper for our research LBS and now doing some experiments 
with maintaining a consistent tree across multiple datacenters (in the US, 
Europe and Asia). Thus, we want to reduce the latency by eliminating 
unnecessary roundtrips between, for example, EU and US-based servers if 
possible. E.g., we can pre-assign particulars branches of the tree (I believe, 
called "containers" in the wiki page) to different ensembles with transparent 
rerouting when needed. So if the server in EU needs to access a namespace 
located in the US it should be forwarded to a different zk-ensemble, but 
hopefully most of the time these servers would coordinate with "local" 
ensemble(s) only. I was thinking about a simpler solution, e.g., just keeping 
distinct ensembles for different geographical zones and reroute those calls 
that have a different "namespace owner". But then I found a wiki page with the 
description of PartitionedZookeeper and figured it might be a right approach.

Please let me know if it goes long the same motivation you have in mind for 
PartitionedZookeeper. Do you have something in code for namespace partitioning? 
I'd be happy to contribute.

> Namespace partitioning in ZK 
> -----------------------------
>                 Key: ZOOKEEPER-646
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-646
>             Project: Zookeeper
>          Issue Type: New Feature
>            Reporter: Kay Kay
> Tracking JIRA for namespace partitioning in ZK 
> From the mailing list (- courtesy: Mahadev / Flavio ) , discussion during Jan 
> 2010 - 
> "Hi, Mahadev said it all, we have been thinking about it for a while, but
> >> haven't had time to work on it. I also don't think we have a jira open for
> >> it; at least I couldn't find one. But, we did put together some comments:
> >>
> >>    http://wiki.apache.org/hadoop/ZooKeeper/PartitionedZookeeper
> >>
> >> One of the main issues we have observed there is that partitioning will
> >> force us to change our consistency guarantees, which is far from ideal.
> >> However, some users seem to be ok with it, but I'm not sure we have
> >> agreement.
> >>
> >> In any case, please feel free to contribute or simply express your
> >> interests so that we can take them into account.
> >>
> >> Thanks,
> >> -Flavio
> >>
> >>
> >> On Jan 15, 2010, at 12:49 AM, Mahadev Konar wrote:
> >>
> > >>> Hi kay,
> > >>>  the namespace partitioning in zookeeper has been on a back burner for a
> > >>> long time. There isnt any jira open on it. There had been some
> > >>> discussions
> > >>> on this but no real work. Flavio/Ben have had this on there minds for a
> > >>> while but no real work/proposal is out yet.
> > >>>
> > >>> May I know is this something you are looking for in production?
> > >>>
> > >>> Thanks
> > >>> mahadev
> "

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