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https://issues.apache.org/jira/browse/CASSANDRA-14874?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16679554#comment-16679554
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Sylvain Lebresne commented on CASSANDRA-14874:
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I'll note that while I have barely spent any time thinking about it, I have a
hunch that getting this perfectly right might not be easy since truncate is not
timestamp based (and not coordinated with reads), but at least having
coordinators check, before sending read-repairs, if they have seen a truncation
since the beginning of the repair would be dead simple and improve this
drastically.
> Read repair can race with truncations
> -------------------------------------
>
> Key: CASSANDRA-14874
> URL: https://issues.apache.org/jira/browse/CASSANDRA-14874
> Project: Cassandra
> Issue Type: Bug
> Components: Local Write-Read Paths
> Reporter: Sylvain Lebresne
> Priority: Minor
>
> While hint and commit log replay handle truncation alright, we don't have
> anything to prevent a read/read-repair to race with {{TRUNCATE}}. In other
> words, you can have a read reading some pre-truncation data, some truncation
> running and removing that data, and then some read-repair mutation from that
> previous read that resurrects some data that should have bene truncated.
> Probably not that common in practice, but can lead to seemingly random data
> surviving truncate.
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