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https://issues.apache.org/jira/browse/ZOOKEEPER-1675?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13618739#comment-13618739
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Jacky007 commented on ZOOKEEPER-1675:
-------------------------------------

Sorry, it has nothing to do with correctness. What I want to tell is we may 
need more codes to achieve a really "strong read".
                
> Make sync a quorum operation
> ----------------------------
>
>                 Key: ZOOKEEPER-1675
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1675
>             Project: ZooKeeper
>          Issue Type: Bug
>    Affects Versions: 3.4.0, 3.5.0
>            Reporter: Alexander Shraer
>
> sync + read is supposed to return at least the latest write that completes 
> before the sync starts. This is true if the leader doesn't change, but when 
> it does it may not work. The problem happens when the old leader L1 still 
> thinks that it is the leader but some other leader L2 was already elected and 
> committed some operations. Suppose that follower F is connected to L1 and 
> invokes a sync. Even though L1 responds to the sync, the recent operations 
> committed by L2 will not be flushed to F so a subsequent read on F will not 
> see these operations. 
> To prevent this we should broadcast the sync like updates.
> This problem is also mentioned in Section 4.4 of the ZooKeeper peper (but the 
> proposed solution there is insufficient to solve the issue).

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