[jira] [Comment Edited] (CASSANDRA-20877) FINALIZED incremental local repair sessions are not cleaned up in case of a range movement

["Stefan Miklosovic (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-20877?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18022193#comment-18022193 ] 

Stefan Miklosovic edited comment on CASSANDRA-20877 at 9/23/25 3:24 PM:
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[~chovatia.jaydeep@gmail.com] does this look OK to you? Trying to get some reviews from "repair people". Thanks!


was (Author: smiklosovic):
[~jchovatia] does this look OK to you? Trying to get some reviews from "repair people". Thanks!

> FINALIZED incremental local repair sessions are not cleaned up in case of a range movement 
> -------------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-20877
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-20877
>             Project: Apache Cassandra
>          Issue Type: Bug
>          Components: Consistency/Repair
>            Reporter: Dmitry Konstantinov
>            Assignee: Dmitry Konstantinov
>            Priority: Normal
>             Fix For: 4.0.x, 4.1.x, 5.0.x, 5.x
>
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> * system.repairs table is local per each Cassandra node.
>  * This table is cleaned up by a periodically running org.apache.cassandra.repair.consistent.LocalSessions#cleanup() job.
>  * The job runs every cassandra.repair_cleanup_interval_seconds (with default = 10 minutes).
>  * The job should delete repair sessions with FINALIZED state which are older than cassandra.repair_delete_timeout_seconds (with default value = 1 day).
>  * Before deleting of a FINALIZED session org.apache.cassandra.repair.consistent.LocalSessions#isSuperseded check is executed for them to ensure if all ranges and tables covered by this session have since been re-repaired by a more recent session. If it is not superseded the session info delete from the table is skipped and a log message is printed:
> {code:java}
> Skipping delete of FINALIZED LocalSession {repairSessionId} because it has not been superseded by a more recent session"{code}
>  * isSuperseded logic allows to delete a repair session info only if all session ranges are covered by some newer session on the node.
> If we added a new node then a set of ranges is moved to it and for these ranges data are not repaired anymore on the old nodes, so isSuperseded always return false for the last session executed before the node adding.
> If we have a big cluster with a lot of nodes added while an incremental repair is executed regularly then we get a lot of non-removable old records in system.repairs table it may slow down startup for Cassandra nodes especially if a large number of tokens is used on the cluster historically.
> A similar issue is with a table removal, the logic consider the last session which was executed for a removed table as non-superseded and keeps it forever.



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