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From Michel Segel <michael_se...@hotmail.com>
Subject Re: How practical is it to add a timestamp oracle on Zookeeper
Date Sun, 21 Apr 2013 16:36:16 GMT
Time is relative.
What does the timestamp mean? 

Sounds like a simple question, but its not. Is it the time your application says they wrote
to HBase? Is it the time HBase first gets the row? Or is it the time that the row was written
to the memstore? 

Each RS has its own clock in addition to your app server.

Sent from a remote device. Please excuse any typos...

Mike Segel

On Apr 16, 2013, at 7:14 AM, yun peng <pengyunmomo@gmail.com> wrote:

> 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

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