[jira] [Updated] (CASSANDRA-15745) Conflicting LWT transactions may be committed during topology change

["Benedict Elliott Smith (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-15745?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Benedict Elliott Smith updated CASSANDRA-15745:
-----------------------------------------------
     Bug Category: Parent values: Correctness(12982)Level 1 values: Unrecoverable Corruption / Loss(13161)
       Complexity: Challenging
    Discovered By: User Report
         Severity: Normal
           Status: Open  (was: Triage Needed)

> Conflicting LWT transactions may be committed during topology change
> --------------------------------------------------------------------
>
>                 Key: CASSANDRA-15745
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-15745
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Feature/Lightweight Transactions
>            Reporter: Konstantin
>            Priority: Normal
>
> Let's consider a cluster which consists of replicas A, B and C.
> We're adding replica D which replaces A.
> A scenario is possible when two conflicting transactions, CAS1 and CAS2, may be committed during replace:
> CAS2 ballot > CAS1 ballot
> CAS2 and CAS1 conflict  on LWT condition, yet both of them may be committed in  case of the following sequence of events:
> Topology change starts, advertises on C
> CAS1 starts on node C, uses {A, B, C, D}
> CAS2 starts on node A, still uses {A, B, C}
> Topology change is advertised on A
> CAS1 prepares on {B, C, D}
> CAS2 prepares and accepts on {A, B}, commits on A
> CAS1 accepts on D, then stops
> Streaming starts, topology change finishes, A is removed
> CAS3 prepares using C and D. It sees the accept of CAS1 and replays it
> Both CAS1 and CAS2 are committed.



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