-Re: How practical is it to add a timestamp oracle on Zookeeper
Jean-Marc Spaggiari 2013-04-16, 13:31
Attachements are not working on the mailing list. However, everyone
using HBase should have the book on its desk, so I have ;)
On the figure 8-11, you can see that client wil contact ZK to know
where the root region is. Then the root region to find the meta, and
BUT.... This will be done only once per client! If you do 10 gets from
your client, once you know where the root region is, you don't need to
query ZK anymore. It will be cached locally.
For your usecase, you might want to take a look at what Ted send.
https://github.com/yahoo/omid/wiki I looked a it quickly and seems to
be a good fit for you.
2013/4/16 yun peng <[EMAIL PROTECTED]>:
> Hi, Jean and Jieshan,
> Are you saying client can directly contact region servers? Maybe I
> overlooked, but I think the client may need lookup regions by first
> contacting Zk as in figure 8-11 from definitive book(as attached)...
> Nevertheless, if it is the case, to assign a global timestamp, what is the
> practical solutions in real production today? since it still needs some
> centralised facility.. Please enlighten me. thanks.
> On Tue, Apr 16, 2013 at 8:19 AM, Jean-Marc Spaggiari
> <[EMAIL PROTECTED]> wrote:
>> Hi Yun,
>> If I understand you correctly, that mean that each time our are going to
>> a put or a get you will need to call ZK first?
>> Since ZK has only one master active, that mean that this ZK master will be
>> called for each HBase get/put?
>> You are going to create a bottle neck there. I don't know how many RS you
>> have, but you will certainly hotspot you ZK server. I'm not sure it's a
>> good idea.
>> 2013/4/16 yun peng <[EMAIL PROTECTED]>
>> > Hi, All,
>> > I'd like to add a global timestamp oracle on Zookeep to assign globally
>> > unique timestamp for each Put/Get issued from HBase cluster. The reason
>> > I
>> > put it on Zookeeper is that each Put/Get needs to go through it and
>> > unique
>> > timestamp needs some global centralised facility to do it. But I am
>> > asking
>> > how practical is this scheme, like anyone used in practice?
>> > Also, how difficulty is it to extend Zookeeper, or to inject code to the
>> > code path of HBase inside Zookeeper. I know HBase has Coprocessor on
>> > region
>> > server to let programmer to extend without recompiling HBase itself.
>> > Does
>> > Zk allow such extensibility? Thanks.
>> > Regards
>> > Yun