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From Ibrahim <i.s.el-san...@newcastle.ac.uk>
Subject RE: Question about the two-phrase commit
Date Wed, 07 Jan 2015 00:08:36 GMT
Ok, this is really interesting. In this case, we can say that the new leader has to re-broadcast
all logged operations,  it doesn’t matter whether the operation gets the acknowledgment
from quorum or not, because the leader can’t distinguish  between committed logged operation
and non-committed logged operation.

I am also thinking, when the ensemble establishes, the leader apply the snapshot in-memory
before log file, in this case the leader will only re-broadcast the operation that hasn’t
got enough majority (quorum) before crashes. If this is true, my above statement will be wrong.

Which one of both statement is correct?

Thank you


From: Alexander Shraer-2 [via zookeeper-user] [mailto:ml-node+s578899n7580740h64@n2.nabble.com]
Sent: Tuesday, January 06, 2015 11:51 م
To: Ibrahim El-sanosi (PGR)
Subject: Re: Question about the two-phrase commit

Yes, if the leader has this operation in its log (not guaranteed if it
wasn't acked by majority in previous ensemble, but possible), the leader
will make sure that a quorum of followers in the new ensemble has this
operation before doing anything else in the new ensemble.


On Tue, Jan 6, 2015 at 3:42 PM, Ibrahim <[hidden email]</user/SendEmail.jtp?type=node&node=7580740&i=0>>

>  Hi Alexander,
> So, you meant that if there is operation loged to the disk but it hasn't
> got
> enough majority, then if the zookeeper servers restart, the new leader will
> re-broadcast the loged operation again to the followers to commit that
> operation.
> Does above what you meant by (NEWLEADER message acts as the accept and
> UPTODATE message acts as commit).
> Am I right?
> Thank you
> Ibrahim
> --
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