[jira] [Commented] (CASSANDRA-11087) Queries on compact storage tables in mixed version clusters can return incorrect results

["Paulo Motta (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-11087?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15121530#comment-15121530 ] 

Paulo Motta commented on CASSANDRA-11087:
-----------------------------------------

Good catch! This would've probably been catch by the upgrade dtests of CASSANDRA-10563, once they're merged in the main upgrade suite which include an intermediate mixed-versions step (not included in the current version) (just letting you know so you can probably reuse those here).

> Queries on compact storage tables in mixed version clusters can return incorrect results
> ----------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-11087
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11087
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Local Write-Read Paths
>            Reporter: Sam Tunnicliffe
>            Assignee: Sam Tunnicliffe
>             Fix For: 3.0.x, 3.x
>
>
> Whilst writing a dtest for CASSANDRA-11045, it becomes apparent that queries on compact storage tables are broken during the 3.0 upgrade (and this has probably been the case since day 1). 
> tl;dr In a cluster with a mix of < 3.0 and 3.0 nodes, reads on COMPACT STORAGE tables may not include all results. 
> To repro: tables are created and data written before any nodes are upgraded to 3.0+, some nodes are then upgraded putting the cluster into a mixed state.
> Now, when a query is run where the coordinator is a < 3.0 node, any 3.0+ replica which has not yet run upgradesstables always returns 0 results.  Once upgradesstables is run, the replica returns the correct results. Likewise, if the data is inserted after the node is upgraded, the results are correct. If the 3.0 node acts as the coordinator, the results are also correct and so once all nodes are upgraded, the problem goes away.
> The behaviour can be seen for both single partition and range requests as [this dtest|https://github.com/beobal/cassandra-dtest/commit/91bb9ffd8fb761ad3454187d2f05f05a6e7af930] demonstrates.



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