[jira] [Commented] (CASSANDRA-9143) Improving consistency of repairAt field across replicas

["Blake Eggleston (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-9143?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15648298#comment-15648298 ] 

Blake Eggleston commented on CASSANDRA-9143:
--------------------------------------------

Just wanted to point out that [~pauloricardomg] found another source of repaired data inconsistency in CASSANDRA-10446. Since streamed data includes the repairedAt value for the in progress session, if the session fails, it's possible that a node will consider data repaired that another node may have never seen.

> Improving consistency of repairAt field across replicas 
> --------------------------------------------------------
>
>                 Key: CASSANDRA-9143
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-9143
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: sankalp kohli
>            Assignee: Blake Eggleston
>            Priority: Minor
>
> We currently send an anticompaction request to all replicas. During this, a node will split stables and mark the appropriate ones repaired. 
> The problem is that this could fail on some replicas due to many reasons leading to problems in the next repair. 
> This is what I am suggesting to improve it. 
> 1) Send anticompaction request to all replicas. This can be done at session level. 
> 2) During anticompaction, stables are split but not marked repaired. 
> 3) When we get positive ack from all replicas, coordinator will send another message called markRepaired. 
> 4) On getting this message, replicas will mark the appropriate stables as repaired. 
> This will reduce the window of failure. We can also think of "hinting" markRepaired message if required. 
> Also the stables which are streaming can be marked as repaired like it is done now. 



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