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https://issues.apache.org/jira/browse/CASSANDRA-16878?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17481459#comment-17481459
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Yifan Cai commented on CASSANDRA-16878:
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The patch is only correct with the precondition that the mutations in the
commit logs are ordered (equivalently, i.e. required schema changes are logged
before the mutations). Looking at the code, I think a mutation won't appear
_before_ this related schema change in the commit log.
- If a mutation is added to the commit log, it means it has passed the
validation, which indicates the required schema change is present, and the
corresponding mutations should be allocated earlier.
- For a mutation that contains non-existing schema arriving before the schema
change, the mutation is rejected during validation, and it does not appear in
the commit log.
> Race in commit log replay can cause rejected mutations
> ------------------------------------------------------
>
> Key: CASSANDRA-16878
> URL: https://issues.apache.org/jira/browse/CASSANDRA-16878
> Project: Cassandra
> Issue Type: Bug
> Components: Legacy/Local Write-Read Paths
> Reporter: Andres de la Peña
> Assignee: Andres de la Peña
> Priority: Normal
> Fix For: 3.0.x, 3.11.x, 4.0.x, 4.x
>
> Time Spent: 1h 50m
> Remaining Estimate: 0h
>
> We don't force order in the execution of replayed mutations and hence a
> mutation can move ahead of or behind a schema change it relies on (e.g.
> added/removed column), which can then cause it to be rejected because of a
> schema mismatch.
> To fix this, we need to identify schema mutations and make sure the log
> enforces their execution after all previous mutations have completed and
> before anything following is started.
> Schema mutations are
> [flushed|https://github.com/apache/cassandra/blob/cassandra-4.0.0/src/java/org/apache/cassandra/schema/SchemaKeyspace.java#L1266-L1271]
> after being applied, so this only would be a problem if the node abruptly
> stops before flushing the schema mutation.
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